In the early 20th century the Texas Oil Boom took hold creating tremendous economic opportunities in Southeast Texas and North Texas. The growth generated by this boom largely passed by Austin at first, with the city slipping from 4th largest to 10th largest in Texas between 1880 and 1920. Bastrop, however, became a significant center for oil drilling and coal mining in the early-to-mid-20th century. San Marcos, and some other communities, established significant manufacturing operations during the world wars substantially diversifying their economies.