Draft:Keystone symbol

The keystone symbol is the name commonly given to the de-facto state emblem of Pennsylvania. It is a stylized keystone (or capstone), an architectural term for a wedge-shaped stone placed at the top of an arch. The shape consists of two isosceles trapezoids, each with the smaller side facing downward, with one being smaller, more flat, and placed on top of the other. The symbol alludes to Pennsylvania's official nickname, The Keystone State. Although the symbol has not been designated as the official state emblem, it is widely used by the Pennsylvanian government and by individuals.

Usage
Each agency of the Pennsylvanian government uses the keystone symbol on its official logo. It is also used on various logos, such as that of the Heinz Company, Little League Baseball, and National Honor Society — both worldwide, and founded in Pennsylvania.

The badge of the 28th Infantry Division is a red keystone symbol. It's flag also shows a keystone symbol. Other parts of the 28th Infantry Division also use keystone symbols on their insignia: the 104th Cavalry Regiment, the 108th Field Artillery Regiment, the 628th Aviation Support Battalion, and the 55th Maneuver Enhancement Brigade. In 2017 the "Keystone Flag" was designed by Tara Stark, a Pennsylvania resident. The flag incorporates the keystone into a tricolor design using the colors on the coat of arms of Pennsylvania as an intentional callback to the symbolism of the existing flag. The design gained significant attention on social media, but is not currently adopted.

History
In September 1899, a military parade in Philadelphia featured a choir of 3,200 school-children and teachers were arranged to display three keystone symbols with the letters "GAR" on them (standing for Grand army of the Republic). By the 1910s, the symbol was somewhat popular, and was used often enough that the average person could recognize it. Shortly after World War I, the Department of Highways (now part of PennDOT) created a system of road signs called keystone markers. These signs were in the shape of the keystone symbol, and were usually blue with a yellow border but could vary due to cultural reasons. These signs used to number in the thousands, but as of 2010, only around 600 exist state-wide.