[2] Originally a small town inhabited by mostly Bavarian Roman Catholics, it was founded December 8, 1842.

In 1992, the borough of St. Marys absorbed the surrounding township of Benzinger and incorporated as a city.

The area is known for its access to outdoor activities, including trout streams and state hunting lands inside the city limits.

Most of that area is unurbanized, and the large size is due to the city's 1992 merger with surrounding Benzinger Township.

The downtown area lies directly on the Eastern Continental Divide, such that water on the eastern side of the city drains into the Atlantic Ocean, while the western side drains to the Gulf of Mexico.

St. Marys Municipal Airport lies in the city's southeastern quadrant and serves general aviation.

It houses preschool through fifth-grade classes for public school students within the city limits; similar services are provided to residents of Fox Township, the Fox Township Elementary School in Kersey.

St. Marys Catholic Elementary School has one building, which is connected to Queen of the World Church.

[13] Straub Brewery, was founded in St. Marys in 1872 by Peter Straub (1850–1913) of Felldorf, Württemberg, Germany, who purchased the Benzinger Spring Brewery from his father-in-law, Francis Xavier Sorg.

Brewing continuously since that time, Straub is the third oldest brewery in the United States and considered an American Legacy Brewery™.

[citation needed] It is still owned and operated by the founding family, now in its seventh generation.