The U.S. Postal Service, formerly the Post Office Department, has a standard color scheme of red, white and blue in 2011. These colors are most recognized on the USPS's collection boxes, which are on street corners throughout the country. However, the color scheme for these boxes has been far from consistent; it changed several times before becoming the color it is today.
The color of collection boxes from their beginning in the 1850s is unknown. The earliest reference to collection box color is found in a work by W.B. Jones in 1889, "The Story of the Post Office." It refers to 800 street letter boxes painted either red or green; the red ones are listed as the most important. It's unclear whether that reference applied to all collection boxes, or just to those in Boston, where the author lived.
In 1903, Assistant Postmaster General, J. Bristow wrote to General Superintendent of the Free-Delivery System, A.W. Machen and referred to the repeated change of collection box colors. He mentioned that "years ago" the color had been dark green, then it was vermilion red, then an aluminum color, then green, then aluminum bronze. This reference suggests that there was no standard color for collection boxes, and that it had changed according to the whims of administrators.
1917 to 1955
Before World War I, the color of collection boxes changed repeatedly. After the war, the War Department gave the Post Office Department a large supply of surplus olive drab paint that was used to coat the collection boxes. Olive drab became the standard color for collection boxes until 1955.
1955 to 1971
On July 4, 1955, Postmaster General Arthur Summerfield declared that collection boxes would be painted red, white, and blue to make them easily recognizable. The paints were of a new, longer-lasting formula.
The Post Office Department was reorganized in 1971 as the U.S. Postal Service. At that time, collection boxes were painted a solid, deep blue color. The boxes were given decals with images of the new Postal Service logo. This color scheme was still in effect in 2011, although in 1993 a new logo appeared.