The town initially grew quickly and prospered as a center of business in the Sweetwater Valley.

By the mid-19th century, Philadelphia had two general stores, a tanning yard, a stillhouse, and a hotel.

[7] On October 20, 1863, during the Civil War, two Confederate cavalry regiments attacked and routed a Union brigade at Philadelphia while conducting maneuvers following the Battle of Chickamauga.

Philadelphia is situated along Sweetwater Creek, which empties into the Watts Bar Lake impoundment of the Tennessee River a few miles to the north.

According to the United States Census Bureau, the city has a total area of 1.6 square miles (4.1 km2), all land.

As of the 2020 United States census, there were 607 people, 278 households, and 213 families residing in the city.