In the USA, there is no law dictating an upper limit for the amount of cash a person can carry. Each individual has the right to carry as much cash as he or she chooses.
Aside from the obvious safety risks posed by carrying large amounts of cash, there are special considerations for withdrawing large sums, and there are Customs requirements for traveling with large sums. Banks can require up to seven days notice for large cash withdrawals, and cash transactions over $10,000 must be reported to the IRS. Traveling in or out of the country with more than $10,000 cash must be documented at the point of arrival or departure with a Customs declaration.