All NFL goal posts are sulfur yellow, and the color is applied by powder coat instead of paint, which tends to chip and fade. That change was made about 10 years ago.

ALLEN PARK - Detroit Lions kicker Matt Prater first kicked on Arena League Football goal posts, which are about half as wide as those used in NFL games, early in his career with the Denver Broncos ...

When the NFL was founded in 1920, it used the ‘H’ design for its uprights and placed them on the goal line. In 1927, the league moved the posts back 10 yards, to the back of the end zone.

How the Football Field Was Designed, from Hash Marks to Goal Posts The American football field as evolved over more than 100 years, and with it, the game. Jimmy Stamp. September 24, 2012.