The development of Mexican oil fields by North American corporations during the 1920s led to a need for reliable transportation into Mexico's interior. As a result, Brownsville soon became a pioneer training center for the now highly technical craft of blind flying, or piloting an aircraft by the use of navigation instruments. In 1929, the Mexican division of Pan American Airways opened a school for instrumentation flying at the Brownsville Airport. The training course was later extended to all divisions of the company.