When : Always August 4th U.S. Coast Guard Day honors the military branch that protects our waters and shorelines. The U.S. Defense Department suggests that this day is largely an internal celebration for all Coast Guard personnel and their families, past and present. But, we'd like to encourage everyone to honor the brave members of this important branch of the military. Celebrate U.S. Coast Guard Day by learning more about the responsibilities and functions of the U.S. Coast Guard. They are now playing an even more extensive role in Homeland Security to protect our country. We salute Coast Guard personnel today and every day. We hope you do, too. Origin of U.S. Coast Guard Day: On August 4, 1790, the Revenue Cutter Service was created by the U.S. Congress. Congress authorized the construction of ten cutters. These ships were built to to enforce U.S. tariff laws. The Revenue Cutter Service was the predecessor the the U.S. Coast Guard. The name "Coast Guard" was first used in 1915.