Aircraft manufacturing began in the 1920s, and Wichita remains a center of the aircraft industry today. In addition, the city also has flour mills, meatpacking plants, and oil refineries. Major manufactures include camping equipment, heaters and air conditioners, and electronics. Wichita has a number of art and historical museums, a zoo, and a planetarium. It is the site of several universities, including Wichita State University (1895). McConnell Air Force Base is nearby.