When the Coast Guard "Reserve" was authorized by act of Congress on June 23, 1939, the Coast Guard was given a legislative mandate to use civilian volunteers to promote safety on and over the high seas and the nation's navigable waters. The Coast Guard Reserve was then a non-military service comprised of unpaid, volunteer U.S. citizens who owned motorboats or yachts.
Two years later, on Feb. 19, Congress amended the 1939 act with passage of the Auxiliary and Reserve Act of 1941. Passage of this act designated the Reserve as a military branch of the active service, while the civilian volunteers, formerly referred to as the Coast Guard Reserve, became the Auxiliary.
February 19 is formally recognized as the birth of the Coast Guard Reserve while June 23 is recognized as the birthday of the Coast Guard Auxiliary.