North Park, at 3010 acres, is the largest park in the system, more than 1000 acres greater than its sister facility, South Park. There are dimensions worth noting about the waters of North Park. The lake is the largest man-made body of water in Allegheny County, flowing over 75 acres, and is bordered by four and one-half miles of natural woodlands. The swimming pool in North Park was once considered the largest in the world; it holds two and a half million gallons of water (compared to say 20-30,000 gallons in a modern city pool). In the '30s and '40s, before pools proliferated in homes and private organizations, the monstrous North Park Pool seemed a logical response to the "bathing" needs of everyone north of Pittsburgh. A large South Park pool was also created, and the two pools, the only major swimming facilities in the county, attracted some 300-500,000 people per season during their first two decades.
The idea of North Park Lake, and of fishing in the lake, was advanced by County Commissioner John J. Kane. When the Old Pine Creek flowing into a marshy area was eventually transformed into a lake, the notion of stocking the lake with fish naturally followed. Some 50,000 people bordered the well stocked lake on the first day of fishing in 1937, and KDKA broadcast the ceremony as Commissioner Kane tossed the first line into the waters.