By 1852 La Porte had become a well-established settlement of considerable size for its time and vicinity, with 5,000 residents. In that same year it was granted a city charter by the Indiana General Assembly, and the first mayor was elected. La Porte continued to grow, attracting numerous diverse industries, the largest of which became the Advance-Rumely company. Advance-Rumely developed and manufactured the Oil-Pull tractor engine, considered to have played a pivotal role in the agricultural development of the Great Plains. By 1869, Advance-Rumely was the largest employer in La Porte.