When it comes to dates in Steelers history, none is more significant than July 8, 1933, because that was when the franchise was founded by Art Rooney Sr.

For the first 7 years of its existence, Rooney's franchise was known as the Pirates, but before the start of the 1940 season he renamed it the Steelers. To commemorate that, Rooney was given a plaque featuring a football-shaped image honoring the city's steel industry with the words "Pittsburgh Steelers Football Club" around the edge.

Even though NFL team logos didn't exist back then, Rooney appreciated the gift and liked the design, and so starting in 1940 that became the first logo identifying the Steelers. It was used almost exclusively as letterhead.

As the NFL clawed for a bigger piece of the professional sports pie after the end of World War II, teams explored ways to attract more attention. As Dan Rooney became more involved in his father's franchise during the late 1950s, he planted the seed for the idea that blossomed into a logo that newspapers used to spruce up its coverage of the team. The "Man on the Beam" logo developed a public profile during the late 1950s, and in 1998 when the NFL instituted a program to promote throwback merchandise the league chose that to represent the Steelers.

In 1948, logos became much more visible when the Los Angeles Rams allowed running back Fred Gehrke, an art major at the University of Utah, to paint horns on their helmets – mainly because he offered to do it for free. The Steelers featured each player's jersey number on both sides of a gold helmet, but things all came together in 1962 when Rooney was approached by Republic Steel, headquartered in Cleveland, and offered the Steelmark as a helmet logo.

The Steelmark is a symbol created by the American Iron and Steel Institute, and it's in the form of a circle that encloses three hypocycloids and the word "Steel." The hypocycloids are three different colors, which eventually came to represent the three elements used to make steel: yellow for coal, orange for ore, and blue for steel scrap.

When the first batch arrived, Rooney wasn't certain they looked all that good on a solid gold helmet. Equipment manager Jackie Hart was instructed to put them only on one side of the helmet as a visual test. The 1962 Steelers finished 9-5 to become the winningest team in franchise history and qualified for the Playoff Bowl, which was a postseason exhibition pitting the second-place teams from each of the NFL's two conferences.

Wanting to commemorate that success, in advance of the Playoff Bowl the Steelers switched to black helmets and ended up liking how the logo popped against a dark background. Rooney's final step was to petition the American Iron and Steel Institute for permission to change the word "Steel" to "Steelers," and when the orange hypocycloid was changed to red, the look was complete and remains unchanged.