The Evergreen Drive-In Theater was built by Donald J. Ruth and opened June 19, 1947 in Mount Pleasant, Pennsylvania. It originally opened as the Ruthorn Drive-In and was renamed the Evergreen Drive-In in 1949. In addition to the Drive-In, Ruth owned Ruth Lumber and Builders Supplies of Scottdale, PA. Upon opening, the theatre had a single screen and parking capabilities for 300 cars. Their first move was Salty O'Rourke, a 1945 gangster movie. 

Ruth's wife, then a widow, sold the theatre to the Michaels family in 1961. Upon acquisition of the theatre, the Michaels family updated the Drive-In; fresh paint, screen resurfacing, and installed new in-car speakers. The Michaels family remained the owners until 1998. It was sold to Joe Warren, of the Warren Theatres in 1999.

Warren Theatres has been in business since 1949, owning and operating a handful of other Drive-Ins and theatres throughout Penssylvania. In 2001 they planned to add two new screens however the terrorist attacks of 9/11 caused them to decide to hold off. In 2002 two new screens were added increasing the car capacity to 500. On

April 18, 2014 the theatre converted to digital projection, a costly but neccessary change for the theatre to stay in business. They currently stay open seven nights a week during their regular season which runs from April through September.