St. Marys is a city in Elk County, Pennsylvania, United States. The population is 12,738 as of the 2020 census. Originally a small town inhabited by mostly Bavarian Roman Catholics, it was founded December 8, 1842. It is home to Straub Brewery and the first Benedictine convent in the United States. In 1992, the borough of St. Marys absorbed the surrounding township of Benzinger and incorporated as a city. Despite its place as the second-largest city by area in Pennsylvania behind Philadelphia, it is one of the state's least densely populated cities.

Elk County is a county in the Commonwealth of Pennsylvania. As of the 2020 United States census, the population was 30,990. Its county seat is Ridgway. The county was created on April 18, 1843, from parts of Jefferson, Clearfield, and McKean Counties. Elk County is named for the now-extinct eastern elk that historically inhabited the region. The county is part of the North Central Pennsylvania region of the state.