Two years later, Earl decided that it might be possible to build a profitable business based on people's fascination with reptiles. He and some friends constructed an 18 by 24 foot building at the top of a long hill about 3 miles south of Rapid City and put a handful of specimens on display. The location was carefully chosen because in those days, cars would often overheat as they reached the top of a long hill. The idea was for them to stop in Reptile Gardens' parking lot to cool their radiators and maybe stay to see the Gardens.

On June 3, 1937, the doors were opened, and the Black Hills Reptile Gardens was officially in business. Admission was 10¢ for adults and 5¢ for children to see the exhibit. That first day of operation Reptile Gardens took in $3.85. Fortunately business improved; by 1941, the business had 15 employees and was showing a profit. World War II slowed business down drastically with gas rationing, while Earl and his pals served in the military as part of the 'Greatest Generation'. After the war, things picked up again, and many new exhibits were added. More improvements were made to the buildings and premises, and business steadily increased throughout the 1950s.