You may check CBP web site for detail.
aRF}FE,u G$$y\e$ http://www.cbp.gov q*4=sf,> YeCS`IXm The following is mentioned in U.S. Customs and Border Protection Declaration Form
dJD8c2G \B~}s } Money And Other Monetary
6w:M_tDM Instruments
<2>Qr(bb You may bring into or take out of the country, including
6` @4i'. by mail, as much money as you wish. However, if
7gcJ.,Z. it is more than $10,000, you will need to report it to
ify}xv CBP. Ask the CBP officer for the Currency Reporting
r5g:#mF" Form (FinCen 105). The penalties for non-compliance
$Q< >MB7 can be severe.
EG[Rda “Money” means monetary instruments and includes U.S.
DF!*S{) or foreign coins currently in circulation, currency, travelers’
wLz@u$u? checks in any form, money orders, and negotiable
"_
i: instruments or investment securities in bearer form.