Customs duties and excise tax, is the right answer.
Following the Revolutionary War, the new government of the United States faced the problem of the national debt. During the course of the war, the federal government had received a massive debt: $54 million including interest. Therefore, the responsibility to solve this problem was assigned to Alexander Hamilton. He recommended that the government consider the entire debt of the federal administration and the states. He introduced a plan of borrowing new money at a lower interest valuation and believed that the income to pay the interest on the federal debt would come from Customs duties and excise dues.
