As I-37 enters the San Antonio city limits, it intersects the northern terminus of US 181. Continuing to the north, it intersects I-410, the inner loop around San Antonio, at a stack interchange. At this junction, the Interstate once again runs concurrently with US 281 which had been concurrent with I-410. Heading north through the south side of San Antonio, I-37 provides access to Brooks City-Base (formerly Brooks AFB). After a cloverleaf interchange at Loop 13, the freeway turns towards the northwest. The highway intersects I-10, which is concurrent with US 90 and US 87, at a stack interchange on the southeastern corner of Downtown. After the interchange, it once again heads north on the east side of Downtown. It passes near the Alamodome, the Tower of the Americas, the River Walk and the Alamo. I-37 ends at the northeastern corner of Downtown at a junction with I-35. US 281 continues to the north as a freeway and provides access to the San Antonio International Airport and later far north central Texas.