Loop 1604 is San Antonio's outer beltway. Although it was built as a two lane rural highway in the 1960s, rapid growth of the San Antonio metro area resulted in the Texas Department of Transportation expanding it to a four lane freeway in the 1980s.

The beltway connects Rondolph AFB, Rolling Oaks Mall, San Antonio Stone Oak, Camp Bullis, the University of Texas at San Antonio, Six Flags Fiesta Texas, La Cantera, and a variety of suburbs.

No interchange between Loop 1604 and US 281 exists, thus motorists must use these highways' respective frontage roads. Currently the Texas Department of Transportation is investigating the implementation of a stack interchange as San Antonio sprawls ever northword.

The Loop 1604/Interstate 10 and Loop 1604/Interstate 35 interchanges are modified cloverleaf interchanges.