You may check CBP web site for detail.
&\3k(j sH//*y http://www.cbp.gov B74L/h .{cka]9WJz The following is mentioned in U.S. Customs and Border Protection Declaration Form
b(hnou S N36<EHq Money And Other Monetary
B.wRZDEvc Instruments
C q/936`O You may bring into or take out of the country, including
^-s'Ad3 by mail, as much money as you wish. However, if
`N+A8 it is more than $10,000, you will need to report it to
[k"@n+% CBP. Ask the CBP officer for the Currency Reporting
U_/sY9gz( Form (FinCen 105). The penalties for non-compliance
mkA1Sh{hX> can be severe.
SDdefB “Money” means monetary instruments and includes U.S.
fM[Qn
*. or foreign coins currently in circulation, currency, travelers’
u7rA8u|TO checks in any form, money orders, and negotiable
~1x,m.f8 instruments or investment securities in bearer form.