Texas currently utilizes 27 area codes. When first established by AT&T and the Bell System in 1947, 214 covered northeastern Texas including Dallas/Fort Worth, 512 covered central and southern Texas including Austin and San Antonio, 713 covered southeastern Texas including Houston, and 915 covered western Texas including El Paso. The most recently added was 726 in 2017 as an overlay to 210. Today, 713 is the most populated with an estimated 4.7 million of the state's 25.1 million residents.
Sources: North American Numbering Plan Administration (NANPA), telecom providers, and the U.S. Census Bureau.