It's a close one as you can see. Listed below are each cities coordinates.

San Antonio: 29°25′N 98°30′W

New Orleans: 29°57′N 90°4′W

Mobile: 30°41′40″N 88°02′35″W

Houston: 29°45′46″N 95°22′59″W

The second largest city in Texas is the home of the Alamo, which was a focal point for Texas in their fight for independence from Mexico. San Antonio is also the home of the Tower of the Americas, the Riverwalk, Fort Sam Houston, Lackland Air Force Base and also Randolph Air Force Base.

San Antonio was one of the ten fastest growing cities in the United States from 2000 to 2010. A bustling metroplex, other attractions in San Antonio include the Alamo Bowl, Seaworld and Six Flags Fiesta Theme park.

More Info: www.wikipedia.org