Austin, Texas is 10 times larger than Vallejo, California.
Area: 933 km2 calculated
Austin is the capital of Texas and the seat of Travis County. Located in Central Texas and the American Southwest, it is the 11th-most populous city in the United States of America and the fourth-most populous city in the state of Texas. Wikipedia
Area: 89 km2 calculated
Vallejo is the largest city in Solano County, California, United States. The population was 115,942 at the 2010 census. It is the tenth most populous city in the San Francisco Bay Area, and is located on the northeastern shore of San Pablo Bay. Vallejo is named for General Mariano Guadalupe Vallejo. Wikipedia