You may check CBP web site for detail.
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]U#[\ Z http://www.cbp.gov %7C%`)T] RP`GG+K The following is mentioned in U.S. Customs and Border Protection Declaration Form
p;n3`aVh *2"
bG1` Money And Other Monetary
2{sD*8&` Instruments
l?@MUsg+ You may bring into or take out of the country, including
^T}}4I_Y by mail, as much money as you wish. However, if
J/]o WC`u it is more than $10,000, you will need to report it to
XUQW;H CBP. Ask the CBP officer for the Currency Reporting
j:v~MrQ7| Form (FinCen 105). The penalties for non-compliance
u"#6_-0y can be severe.
wv7p,9Z[ “Money” means monetary instruments and includes U.S.
7}#*3*] or foreign coins currently in circulation, currency, travelers’
L.IoGUxD checks in any form, money orders, and negotiable
yd0=h7s instruments or investment securities in bearer form.