In 1915 the Revenue Service and the Life-Saving Service combined to form the U.S. Coast Guard. The new service soon had its distinctive uniform characteristics. By the 1920s two major changes were seen in Coast Guard uniforms. First was the adoption of the double-breasted service coat similar to that still worn by the U.S. Navy. This was worn without shoulder straps, and rank designations were on the lower sleeve, with the familiar shield device above the rank stripes. Enlisted men, below petty officer, adopted the Navy-style white duck hat, though the traditional Donald Duck flat cap remained standard. The vessel name on the hat ribbon was to read, for example: U.S.S. Manning, C.G.

The advent of Coast Guard aviation came in the 1920s. The working dress for aviators, all ranks above petty officer, was forest-green gabardine or serge for winter and khaki-colored cotton for summer. The jacket had three buttons, a rolling collar with notch lapel, and four outside pockets (the lower to be of the bellows style). The pockets had flaps and the back had a bellows pleat from the shoulder to the sewn in waist belt. Green shoulder boards with black rank and shield devices were worn with the winter uniform. The khaki shirt had a soft collar worn with a black tie. The aviator badge was a winged, fouled anchor with shield, worn on the left breast. A folding-type flying cap was also authorized, edged in black and gold silk for commissioned and chief warrant officers.

In 1941, for the first time, Coast Guard uniforms became officially a modification of Navy regulations. The garments themselves were the same as naval uniforms and included the khaki undress combination with sewn in belt. Both services used the "combination cap": the officer's peaked headgear with interchangeable covers to match khaki, white or winter uniforms. Only the distinguishing corps devices, buttons, shoulder marks, etc., were distinctively Coast Guard. The officer's cap device for the Coast Guard was the most obvious difference. It consisted of a large spread eagle with shield, with a single horizontal anchor held in the eagle's talons. The naval device had, and still has, a smaller eagle over crossed anchors. Also, the naval eagle was silver; the Coast Guard's, gold.

The Coast Guard uniform coat also continued to have the national shield placed above the sleeve rank stripes. Coast Guard gilt buttons centered their design on a perpendicular anchor, with a rope like inner-rim. The Naval button consisted of an eagle, facing Dexter over a horizontal anchor.

It should also be noted that the Coast Guard accompanied the Navy in the short-lived adoption of a gray undress uniform. This uniform, which was a dark steel gray, cut in the khaki single-breasted pattern, was to be a cost-cutting replacement for both the khaki and double-breasted navy blue (black) uniforms. As with the other uniforms, it was complete with a gray cover for the combination cap. It was adopted in 1943 and phased out in 1947, when it became obvious that the Navy was not interested in abandoning the double-breasted uniform.

The interchangeability with Navy uniforms continued until after the transfer of the Coast Guard to the Department of Transportation and the subsequent adoption of today's lighter blue, single-breasted uniform. (Today, the only uniforms still identical to the Navy's are the officer's summer white service and full dress combinations.) The only non-interchangeable uniform was that of the enlisted surfmen adopted in 1943. This was single-breasted and worn by mounted beach patrols and port security personnel.

The SPAR uniform of World War II was designed like the navy's female uniform although Coast Guard emblems were worn on the lapels. The winter uniform was dark blue; the summer was gray/blue seersucker. There have been few major changes to the women's uniform over the years. Certain items have been phased in and out and there have been modifications to the style and fit but the uniform has remained fairly similar.

The present enlisted uniform marked the first major change in enlisted men's uniforms in over a century. Dissatisfaction with the old traditional sailor suit jumper goes back decades but tradition held on. Two explanations were given for the change to the blue uniforms under Commandant Chester R. Bender. The first was to create a distinctly different uniform from that of the Navy and to solidify the fact that the Coast Guard was a separate organization. The second reason was to update the uniform to be consistent with contemporary society. The particular shade of blue was chosen because it was different from the shades used by the other services.

Coast Guard uniforms have seen two basic trends in their history. One marked a similarity to the uniforms of the U.S. Navy, the other was to have totally different uniforms from that sister service. Through most of this history, the similarities have been the most prevalent and for many years the sole differences were in the insignia and ornaments. Today, the blue uniform is probably the most distinctive since the day of the unloved gray uniform of the 1840s, but today's blues have the distinct advantage of retaining the blue color, as appropriate for a service steeped in serving on the seas.