The United States Senate has introduced a bill that would require all travelers entering the U.S. to declare digital currency holdings in excess of $10,000. Despite concerns raised by the invasive nature of the bill, the likelihood of it being passed is extremely low simply due to the incredibly challenging infrastructure that would be required.
In fact, the new bill is actually a reintroduction of an older bill that was originally introduced in 2011. The 2011 bill never made it out of sub-committee deliberation.
Read more here: https://bitcoinmagazine.com/articles/us-bill-requiring-travelers-declare-digital-currencies-resurfaces/