From Wikipedia:

The Fresno Yosemite International Airport opened as a military airfield in June 1942, just six months after Japan’s attack on Pearl Harbor, leading the United States to enter World War II. The new airfield was named Hammer Field and was used by the United States Army Air Forces as a training facility for the new pilots of the Fourth Air Force. It had a single northwest/southeast oriented runway with a length of 7,200 feet (now runway 11L/29R).^[3]

At the time, civil and commercial aviation used Chandler Field that had opened in November 1929.^[4] Chandler is 1.5 miles (2.4 km) west of downtown Fresno, on a small site. Less than a decade after it opened, it was clear that the small runway at Chandler would not be able to accommodate coming larger airliners.^[4]

After World War II, Hammer Field was inactivated by the Army Air Forces and the city of Fresno saw an opportunity to use the site to create a commercial airport much larger than Chandler Field. In 1946 the War Assets Administration reallocated the property to the city, which immediately began construction on a passenger terminal on the northeast side of the airfield. In 1948, the newly renamed Fresno Air Terminal (FAT) opened. Trans World Airlines (TWA) and United Airlines flights to San Francisco/Oakland and Los Angeles moved from Chandler Field to the newly opened airport. Chandler Field was retained by the city of Fresno as a reliever airport and continues to operate as the Fresno Chandler Executive Airport.^[5][4]