现金不是钞票。

Money and Other Monetary Instruments | U.S. Customs and Border Protection

以下定义不包括银行卡。

What is a “Monetary Instrument”?

For reporting purposes, "monetary instruments" include a variety of instruments such as:

• U.S. or foreign coins and currency.
• Traveler’s Checks in any form.
• Negotiable instruments (including checks, promissory notes, and money orders) that are either in bearer form, endorsed without restriction, made of a fictitious payee, or otherwise in a form that the funds can be transferred to another person.
• Incomplete instruments (including checks, promissory notes, and money orders) signed, but with the payee’s name omitted; and   Securities or stock in bearer form or otherwise in a form that the funds can be transferred to another person.