The County Branch, renamed Mid-County in 1951, was established in 1931. Construction of a new building began in 1957 with funds raised in the 1955 Capital Fund Campaign. In 1969, a new addition was dedicated with club rooms, offices and an indoor-outdoor gymnasium. The gymnasium was later enclosed, four racquetball courts added in 1978, and a running track built around the top of the gym in 1982.
In 1991, construction was completed on a 25,000 square foot addition featuring a Nautilus center, multi-purpose room, locker rooms, administrative offices, and a 25-meter, L-shaped pool with a diving well. Renovation of the existing facility, including a mini-gymnasium, aerobics center, multi-purpose room and child care center, was completed in 1992.
The Vision 2000 Capital Development Program allowed for the expansion of the strength-training center. Space was converted to an additional classroom for the ECEC center.
In 2011, the aerobics center was converted to a cycling studio and a functional training room.