Coast Guard Day is held every August 04 to commemorate the founding of the United States Coast Guard as the Revenue Marine on August 4, 1790, by then-Secretary of the Treasury Alexander Hamilton. On that date, U.S. Congress, guided by Hamilton, authorized the building of a fleet of the first ten Revenue Service cutters, whose responsibility would be enforcement of the first tariff laws enacted by the U.S. Congress under the U.S. Constitution.
Source: Wikipedia