I-37 transitions to a rural setting once outside of the Corpus Christi city limits on its way to Mathis and Lake Corpus Christi. It continues on to the northwest and intersects US 59 (future I-69W) east of George West. It begins paralleling US 281 to the east before the two intersect and have a concurrency north of Three Rivers near Choke Canyon Reservoir. U.S. Highway 281 Alternate (US 281 Alt) splits off from I-37 near Sunniland and parallels I-37 before rejoining north of Campbellton. The two routes remain concurrent until US 281 splits off to head to Pleasanton, while I-37 bypasses the city to the east. After US 281 leaves towards the northwest, I-37 turns to the north towards San Antonio.