FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                 
                Plaintiff-Appellee,              No. 07-30311
               v.                                 D.C. No.
TINA MICHELLE NADER,                           CR-06-00106-RFC
             Defendant-Appellant.
                                          

UNITED STATES OF AMERICA,                       No. 07-30316
                Plaintiff-Appellee,                D.C. No.
               v.                               CR-06-00106-
MARILYN LAKE,                                      RFC-02
            Defendant-Appellant.
                                                 OPINION


         Appeal from the United States District Court
                 for the District of Montana
         Richard F. Cebull, District Judge, Presiding

                    Submitted July 8, 2008*
                      Seattle, Washington

                    Filed September 5, 2008

   Before: Kim McLane Wardlaw, Richard R. Clifton, and
              N. Randy Smith, Circuit Judges.

                    Opinion by Judge Clifton

  *The panel unanimously finds this case suitable for decision without
oral argument. See Fed. R. App. P. 34(a)(2)(C).

                               12351
12354               UNITED STATES v. NADER


                         COUNSEL

Nathan J. Hoines, Hoines Law Office, Great Falls, Montana,
for defendant-appellant Tina Nader.

Mark S. Werner, Federal Defenders of Montana, Billings,
Montana, for defendant-appellant Marilyn Lake.

Kurt G. Alme, Assistant United States Attorney, Billings,
Montana, for the plaintiff-appellee.


                          OPINION

CLIFTON, Circuit Judge:

   Tina Nader and Marilyn Lake, operators of a prostitution
business, appeal their convictions for violating the Travel Act,
18 U.S.C. § 1952. Among other things, the Travel Act prohib-
its the use of “any facility in interstate or foreign commerce”
                         UNITED STATES v. NADER                       12355
with intent to further certain unlawful activity, including prosti-
tution.1 Nader and Lake used telephones to conduct their
unlawful prostitution business, but there is no evidence of any
calls that crossed state lines. This presents the question
whether telephone calls within a single state—intrastate rather
than interstate calls—can violate the Travel Act.

   Nader and Lake argue that the facility at issue must actually
be used in interstate commerce in order to violate the Travel
Act. In support of this position, they argue that Congress
showed its intent to require actual interstate activity by draft-
ing the Travel Act to prohibit the use of “any facility in inter-
state or foreign commerce” rather than the use of “any facility
of interstate or foreign commerce.” They also argue that their
conduct falls outside the Travel Act’s primary legislative pur-
pose, which was to target organized crime, particularly crime
bosses who supervise illegal activities in one state while
residing in another. The government responds that Nader and
Lake’s interpretation is at odds with the plain meaning of the
Travel Act because the phrase “in interstate or foreign com-
merce” plainly modifies the word “facility,” not the word
“uses.” The government also argues that Congress intended
the terms “in” and “of” to be interchangeable, since it used
them interchangeably in the related federal murder-for-hire
statute.
  1
   The Travel Act provides:
      Whoever travels in interstate or foreign commerce or uses the
      mail or any facility in interstate or foreign commerce, with intent
      to . . . otherwise promote, manage, establish, carry on, or facili-
      tate the promotion, management, establishment, or carrying on,
      of any unlawful activity, and thereafter performs or attempts to
      perform . . . [such] an act . . . shall be fined under this title,
      imprisoned . . . or both . . . .
18 U.S.C. § 1952(a) (1990) (emphasis added). The Travel Act also defines
“unlawful activity” to include “any business enterprise involving . . . pros-
titution offenses.” 18 U.S.C. § 1952(b).
12356                   UNITED STATES v. NADER
  The government’s interpretation of the Travel Act is the
more sensible. We affirm Nader and Lake’s convictions and
hold that intrastate telephone calls made with intent to further
unlawful activity can violate the Travel Act because they
involve use of a facility in interstate commerce.

I.       Background

   Nader owned and operated a massage studio in Billings,
Montana from 1994 to 2004, and another massage studio in
Great Falls, Montana from 1993 to 2006. Lake managed the
Billings studio and worked for Nader until 2003 or 2004. It
is undisputed that the businesses involved prostitution. Card
catalogs show that the two businesses had approximately
5000 customers from Montana and at least five other states.2
Many of the prostitution transactions were initiated by a tele-
phone call from the customer.

   Nader and Lake were indicted for violating 18 U.S.C.
§§ 1952 and 2 by using the telephone to carry on a business
enterprise involving prostitution in violation of Montana Code
Ann. § 45-5-601. The government notified Nader and Lake
that it intended to prove that they used a “facility in interstate
or foreign commerce” with evidence of only intrastate tele-
phone calls. Nader and Lake jointly moved to dismiss the
indictment, arguing that their intrastate use of the telephone
was not the use of a “facility in interstate or foreign com-
merce” under the Travel Act. The district court denied the
motion. Nader and Lake pled guilty pursuant to plea agree-
ments in which they expressly reserved their right to appeal
the denial of their joint motion to dismiss. Lake was sen-
tenced to 30 months imprisonment and two years of super-
     2
    While some of Nader and Lake’s customers came from other states,
this fact is insufficient by itself to support a violation of the Travel Act.
Rewis v. United States, 

, 811 (1971) (“But we are unable to
conclude that conducting a gambling operation frequented by out-of-state
bettors, by itself, violates the [Travel] Act.”).
                    UNITED STATES v. NADER                 12357
vised release. Nader was sentenced to 46 months
imprisonment and two years of supervised release. Both were
released pending appeal. These timely appeals followed and
were consolidated.

II.   Discussion

  “We review de novo a district court’s refusal to dismiss an
indictment when the refusal is based on an interpretation of a
federal statute.” United States v. Fitzgerald, 

,
1102 (9th Cir. 1998) (citing United States v. Gomez-
Rodriguez, 

, 1264 (9th Cir. 1996) (en banc)).

   [1] Whether the Travel Act reaches intrastate telephone
calls is a question of first impression in this Circuit. We note
at the outset that this is a question of congressional intent, not
congressional power. Nader and Lake correctly do not contest
that Congress has the power to regulate intrastate telephone
calls. In United States v. Lopez, the Supreme Court identified
“three broad categories of activity that Congress may regulate
under its commerce power.” 

, 558-59 (1995).
Telephones are instrumentalities of interstate commerce that
fall within the second Lopez category. United States v. Dela
Cruz, 

, 625 (9th Cir. 2004); United States v.
Clayton, 

, 1117 (9th Cir. 1997). At issue is
whether Congress intended to regulate intrastate telephone
calls by the language it used in the Travel Act.

   In answering this question, we first consider the plain
meaning of the statute’s text. Jonah R. v. Carmona, 

, 1005 (9th Cir. 2006). If the terms are ambiguous, we
may look to other sources to determine congressional intent,
such as the canons of construction or the statute’s legislative
history. 

We may consider related statutes because
“statutes dealing with similar subjects should be interpreted
harmoniously.” 

(quoting Jett v. Dallas Indep. Sch.
Dist., 

, 738-39 (1989) (Scalia, J., concurring)).
Titles are also an appropriate source from which to discern
12358               UNITED STATES v. NADER
legislative intent. Goodcell v. Graham, 

, 587 (9th
Cir. 1929) (citing Holy Trinity Church v. United States, 

, 462 (1892)).

  A.    Whether the Facility Must Be Used in a Manner that
        Crosses State Lines

   [2] The Travel Act provides that “[w]hoever . . . uses the
mail or any facility in interstate or foreign commerce” with
intent to carry on unlawful activity is guilty of a crime. 18
U.S.C. § 1952(a). Nader and Lake argue that they did not vio-
late the Travel Act because the government has not proved
that any telephone calls crossed state lines. Under Nader and
Lake’s interpretation, the facility at issue must actually be
used in interstate commerce, so the phrase “in interstate or
foreign commerce” in the Travel Act must modify the verb
“uses,” not the noun “facility.” But a common sense reading
of the plain language of the Travel Act shows that it does not.
In the predicate “uses the mail or any facility in interstate or
foreign commerce,” the prepositional phrase “in interstate or
foreign commerce” modifies the noun “facility,” not the verb
“uses.” Congress placed the phrase next to the word “facili-
ty,” which strongly supports the conclusion that the phrase
modifies that word. See The Chicago Manual of Style ¶ 5.167
(15th ed. 2003) (“A prepositional phrase with an adverbial or
adjectival function should be as close as possible to the word
it modifies to avoid awkwardness, ambiguity, or unintended
meanings.”); William Strunk, Jr. & E. B. White, The Ele-
ments of Style 30 (4th ed. 2000) (“Modifiers should come, if
possible, next to the words they modify.”). No court has held
that the phrase “in interstate or foreign commerce” modifies
“uses.” Even the Sixth Circuit, which held that the intrastate
use of the mail cannot support a violation of the Travel Act,
based its holding on other aspects of the statute. See United
States v. Barry, 

, 1095 (6th Cir. 1989). The
plain language of the statute is unambiguous. The facility
itself, not its use, must be in interstate commerce.
                       UNITED STATES v. NADER                       12359
   [3] The weight of authority from other circuits supports this
reading. The Eighth Circuit has held that the intrastate use of
an ATM is the use of a “facility in interstate or foreign com-
merce” under the Travel Act. United States v. Baker, 

, 275 (8th Cir. 1996). This holding is possible only if the
word modified is “facility.” The Second and Fifth Circuits
have held that the intrastate use of the mail can support a vio-
lation of the Travel Act. United States v. Heacock, 

, 255 (5th Cir. 1994); United States v. Riccardelli, 

, 830 (2d Cir. 1986). Both cases involved the pre-
1990 version of the Travel Act, which prohibited the use of
“any facility in interstate or foreign commerce, including the
mail.” Both concluded based on this language that the mail is
a facility in interstate commerce. If the intrastate use of the
mail can violate the Travel Act, and the mail is a facility in
interstate commerce, then the intrastate use of a facility in
interstate commerce can violate the Travel Act. This is possi-
ble only if the word modified is “facility.”3 While these cases
involve facilities other than the telephone, their holdings
require a grammatical construction of the Travel Act that
forecloses Nader and Lake’s interpretation. That the cases
arise under different circumstances does not render them any
less applicable here, since the phrase “in interstate or foreign
commerce” modifies the same word no matter the facts of the
case.

  [4] While the statutory language is unambiguous, we
observe that three circuits, including the Sixth, have explicitly
concluded that the phrase modifies “facility” when construing
nearly identical language in the related murder-for-hire statute.4
  3
     The 1990 amendment to the Travel Act, which was entitled “clarifica-
tion of applicability of [the Travel Act] to all mailings in furtherance of
unlawful activity,” made clear that intrastate mailings can violate the
Travel Act. Pub. L. No. 101-647, tit. XVI, sec. 1604, 104 Stat. 4789, 4843
(Nov. 29, 1990); United States v. Marek, 

, 318 (5th Cir.
2001) (en banc).
   4
     At the time the three cases cited above were decided, the murder-for-
hire statute provided:
12360                  UNITED STATES v. NADER
See United States v. Richeson, 

, 660 (7th Cir.
2003) (holding that the intrastate use of the telephone can sup-
port a violation of the murder-for-hire statute); United States
v. Cope, 

, 771 (6th Cir. 2002) (holding that the
intrastate use of the mail can support a violation of the
murder-for-hire statute); United States v. Marek, 

, 316 (5th Cir. 2001) (en banc) (holding that the intrastate
use of Western Union can support a violation of the murder-
for-hire statute). That the phrase modifies “facility” in the
related murder-for-hire statute weighs in favor of reading the
Travel Act the same way. See Jonah 

.

  B.    Whether Intrastate Telephone Calls Involve the Use of
        a Facility “in” Interstate Commerce

   [5] Nader and Lake concede that the telephone is a facility
of interstate commerce. They argue, however, that Congress
intended to require actual interstate activity by drafting the
Travel Act to prohibit the use of “any facility in interstate or
foreign commerce.” 18 U.S.C. § 1952(a) (emphasis added).
Several courts, including ours, have recognized a distinction
between the phrases “in interstate commerce” and “of inter-
state commerce” in the context of other statutes. In Spilker v.
Shayne Labs., Inc., 

, 525-26 (9th Cir. 1975), we

    (a) Whoever travels in or causes another (including the intended
    victim) to travel in interstate or foreign commerce, or uses or
    causes another (including the intended victim) to use the mail or
    any facility in interstate or foreign commerce, with intent that a
    murder be committed . . . . shall be fined under this title or
    imprisoned . . . or both.
    (b) As used in this section . . .
    ....
    (2) “facility of interstate or foreign commerce” includes means of
    transportation and communication . . . .
18 U.S.C. § 1958 (1996) (emphasis added).
                        UNITED STATES v. NADER                       12361
joined several other circuits in holding that the intrastate use
of the telephone constitutes the use of an “instrumentality of
interstate commerce” under § 10 of the Securities Exchange
Act of 1934 (“1934 Act”). Spilker contrasted the 1934 Act
with the Securities Act of 1933, which contained the phrase
“ ‘instrumentality in interstate commerce.’ ” 

(emphasis added) (quoting Dupuy v. Dupuy, 

,
642-43 (5th Cir. 1975)). Spilker reasoned that “a number of
courts have considered use of the preposition ‘of’ rather than
‘in’ in itself highly persuasive that intrastate telephone com-
munications are within the purview of the 1934 Act.” 

511 F.2d at 642-43). The Sixth Circuit relied
on a similar securities case from its circuit in concluding that
intrastate mailings cannot support a violation of the Travel Act.5
See 

(citing Aquionics Acceptance
Corp. v. Kollar, 

, 1228 (6th Cir. 1974)); see
also United States v. De Sapio, 

, 448
(S.D.N.Y. 1969) (concluding that intrastate telephone calls
cannot support a violation of the Travel Act).

  [6] We attach no special significance to the use of the prep-
osition “in” rather than “of” in the Travel Act. While the lan-
guage may admit of some ambiguity, we decline to apply
Spilker and the other securities cases because they construe
unrelated statutes not at issue here. See United States ex rel.
Chicago, New York & Boston Refrigerator Co. v. Interstate
Commerce Comm’n, 

, 295 (1924) (“[B]ecause
words used in one statute have a particular meaning they do
not necessarily denote an identical meaning when used in
another and different statute.”); United States v. King, 

, 504 (9th Cir. 1973) (“The fact that [Congress] used
  5
    The Fifth Circuit, construing the murder-for-hire statute, distinguished
a similar securities case from its circuit and reached the opposite conclu-
sion: that intrastate activity can support a violation of the Travel Act. See

n.44 (distinguishing 

).
The Second and Seventh Circuits have adopted Marek’s approach. See
United States v. Perez, 

, 304-05 (2d Cir. 2005); 

.
12362                  UNITED STATES v. NADER
different language to achieve the same result in a totally unre-
lated statute is irrelevant.”). Moreover, these securities cases
do not construe the language that is at issue here. They do not
affirmatively hold that “in interstate commerce”—the lan-
guage in both the 1933 Act and the Travel Act—requires
actual interstate activity. The 1934 Act was at issue in Spilker
and the other securities cases, not the 1933 Act. The 1934 Act
contains only the phrase “of interstate commerce.”

   [7] We look, instead, to the murder-for-hire statute, which
is closely related to the Travel Act.6 The murder-for-hire stat-
ute supports the conclusion that Congress did not intend to
require actual interstate activity by using the phrase “in inter-
state or foreign commerce” in the Travel Act. Before it was
amended in 2004, the murder-for-hire statute prohibited the
use of “any facility in interstate or foreign commerce, with
intent that a murder be committed.” 18 U.S.C. § 1958(a)
(1996) (emphasis added). The statute’s definitional section,
however, defined the phrase “facility of interstate or foreign
commerce,” language which did not appear anywhere else in
the statute. 18 U.S.C. § 1958(b) (1996) (emphasis added).7
Three circuits have concluded, based largely on this differ-
ence, that Congress intended the two phrases to be inter-
changeable. See United States v. Perez, 

, 304-05
  6
     The sequential numbering of the Travel Act, 18 U.S.C. § 1952, and the
original version of the murder-for-hire statute, 18 U.S.C. § 1952A (1985),
as well as their parallel language, overlapping subject matter, and legisla-
tive histories show that the murder-for-hire statute was intended to supple-
ment the Travel Act. See 

n.29 (citing United
States v. Edelman, 

, 794 (5th Cir. 1989) (quoting S. Rep. No.
98-225, at 306 (2d Sess. 1988), reprinted in 1984 U.S.C.C.A.N 3182,
3485)); 

. Congress later renumbered the
murder-for-hire statute, codifying it at 18 U.S.C. § 1958. See Pub. L. No.
100-690, tit. VII, sec. 7053(a), 102 Stat. 4181, 4402 (Nov. 18, 1988).
   7
     The definitional section of the murder-for-hire statute provided: “As
used in this section . . . ‘facility of interstate or foreign commerce’
includes means of transportation and communication . . . .” 18 U.S.C.
§ 1958(b) (1996).
                    UNITED STATES v. NADER                 12363
(2d Cir. 2005) (per curiam); 

;

. But see United States v. Weathers,

, 342 (6th Cir. 1999). Any other interpretation
“is difficult to square with the structure of the statute” because
“[i]f the phrases have different meanings, then § 1958(b)
defines a phrase with no application to the substantive
offense.” 

. That Congress intended the
two phrases to be interchangeable in the murder-for-hire stat-
ute supports the view that its use of one rather than the other
in the Travel Act has no special significance. See Jonah 

.

   Congress amended the substantive section of the murder-
for-hire statute to conform with its definitional section in
2004. Both sections now contain the phrase “of interstate or
foreign commerce.” The 2004 amendment is entitled “clarifi-
cation of definition,” even though it changed the substantive
section of the murder-for-hire statute, not the definitional sec-
tion. Pub. L. No. 108-458, tit. II, sec. 6704, 118 Stat. 3638,
3766 (Dec. 17, 2004). That Congress clarified the definition
by changing the substantive section suggests that the content
of the definitional section and the content of the substantive
section were the same before the amendment, i.e., that “in”
and “of” were (and still are) interchangeable. If they were not,
then we would expect the 2004 amendment either to have
changed the definitional section rather than the substantive
section, or not to have purported to be merely a clarification
of the definition.

  [8] Accordingly, intrastate telephone calls involve the use
of a facility “in” interstate commerce.

  C.   Legislative Purpose

   [9] Nader and Lake argue that we should construe the
Travel Act narrowly because their conduct falls outside its
primary legislative purpose. See 

(“It
is a cardinal canon of statutory construction that statutes
12364               UNITED STATES v. NADER
should be interpreted harmoniously with their dominant legis-
lative purpose.”). The primary legislative purpose of the
Travel Act was to target organized crime, particularly the “top
men of organized crime” who oversee illegal activities in one
state while residing in another. 107 Cong. Rec. 13942, 13943
(1961); The Attorney General’s Program to Curb Organized
Crime and Racketeering: Hearings Before the Comm. on the
Judiciary, United States Senate, 87th Cong. 15-16 (1st Sess.
1961) (statement of Attorney General Robert F. Kennedy);
see Rewis v. United States, 

, 812 & n.6 (1971).
No aspect of that purpose is implicated here, since Nader and
Lake were involved in local prostitution businesses, not orga-
nized crime, and they did not reside out-of-state. The statute,
however, is worded broadly. Its plain text prevents us from
reading it to encompass only cases that involve organized
crime or interstate criminal enterprises. To the extent the stat-
ute is ambiguous about whether the telephone is a facility “in”
interstate commerce, the other sources of meaning discussed
above weigh more heavily against a narrow construction than
its legislative purpose weighs in favor of one.

  D.    The Rule of Lenity

   [10] Nader and Lake argue that we should apply the rule of
lenity because the Travel Act is ambiguous. They rely in part
on Rewis, where the Supreme Court applied the rule of lenity
when construing the interstate travel aspect of the Travel 

. The rule of lenity “requires ambiguous crimi-
nal laws to be interpreted in favor of the defendants subjected
to them.” United States v. Santos, 

, 2025
(2008). The rule of lenity, however, “is rooted in fundamental
principles of due process which mandate that no individual be
forced to speculate, at peril of indictment, whether his con-
duct is prohibited.” Dunn v. United States, 

, 112
(1979). Nader and Lake were not “forced to speculate”
because they knew that their conduct was illegal. Accord

.
                    UNITED STATES v. NADER                 12365
   [11] The rule of lenity applies only where “after seizing
every thing from which aid can be derived, the Court is left
with an ambiguous statute.” Smith v. United States, 

, 239 (1993) (refusing to apply rule of lenity where defen-
dant had been convicted of using a firearm in the commission
of a drug trafficking crime, but used the firearm only for bar-
ter, not as a weapon) (internal quotation marks omitted). The
language of the statute must be “grievously ambiguous.”
United States v. Devorkin, 

, 469 (9th Cir. 1998)
(citing Chapman v. United States, 

, 463 (1991)).
We have resolved any ambiguity about the portions of the
Travel Act at issue here with the aid of the related murder-for-
hire statute. See 

. This case is therefore
unlike 

, which involved an aspect of
the Travel Act not at issue here.

  E.   Federalism

   [12] Nader and Lake argue that interpreting the Travel Act
broadly offends principles of federalism. “[I]f Congress
intends to alter the usual constitutional balance between the
States and the Federal Government, it must make its intention
to do so unmistakably clear in the language of the statute.”
Will v. Mich. Dep’t of State Police, 

, 65 (1989)
(internal quotation marks omitted). Nader and Lake argue that
the Travel Act is not unmistakably clear, and that interpreting
it broadly enough to encompass their conduct would alter this
delicate balance. The Travel Act establishes only concurrent
federal jurisdiction over what are already state or local crimes,
however. See 

(quoting S. Rep. No.
98-225, at 304-05 (1984), reprinted in 1984 U.S.C.C.A.N.
3182, 3484). The federal government cannot usurp state
authority via the Travel Act because a state must first decide
that the conduct at issue is illegal. The Travel Act also does
not render state or local law enforcement agencies any less
able to fight crime; it supplements, not supplants, their capa-
bilities. While there may be valid questions as to the wisdom
of drafting such a broad statute or applying it in the context
12366                UNITED STATES v. NADER
of local prostitution businesses like the ones in this case, these
are policy issues within the discretion of the other branches.
They raise no federalism concerns.

III.    Conclusion

   We hold that intrastate telephone calls made with intent to
further unlawful activity can violate the Travel Act because
the telephone is a facility in interstate commerce.

  AFFIRMED.