The green dress uniform worn by the US Army will be phased out of use by the end of 2014. To streamline the dress uniforms required by the US Army, all units will be switching to the blue uniform. It is actually a return to traditional military dress.
In October of 1779, General Washington issued a general order "prescribing blue coats with differing facings for the various state troops, artillery, artillery artificers and light dragoons." Forty years later, the Adjutant & Inspector General's Office established "Dark blue is the National colour. When a different one is not expressly prescribed, all uniform coats, whether for officers or enlisted men, will be of that colour."