Why is Pennsylvania the keystone

The Keystone State

Pennsylvania's essential role in the founding of the United States earned it the nickname, the “Keystone State.” The term “keystone” comes from architecture and refers to the central, wedge-shaped stone in an arch, which holds all the other stones in place.

https://www.pa.gov/guides/state-symbols/#:~:text=The%20Keystone%20State,the%20other%20stones%20in%20place.

>>11321394

I don't fully know. But it goes on to say:

"During the early days of our nation, Pennsylvania held a key position geographically, economically, and politically."