[1] In 1906, Harry Clay Trexler started purchasing farms in Lowhill and North Whitehall townships to create a preserve to help protect bison, elk, and white-tailed deer.

He purchased a total of 36 farms comprising 1,108 acres (448 ha) before he died, and then bequeathed the land to Lehigh County.

When it opened, the zoo included petting and feeding exhibits and exotic animals from Africa, Asia, and Australia.

[5] In 2004, with the original purpose of saving native species accomplished, the county opened the entire preserve to the public.

[5] In 2009, the zoo was participating in three Species Survival Plans (SSP): African penguin, mongoose lemur, and scimitar-horned oryx.