sentences:  US 281 and I-37 then overlap north into Downtown San Antonio until I-37 ends at I-35.US 281 continues north from Downtown San Antonio as the McAllister Freeway, intersecting I-410 again at a stack interchange in Uptown San Antonio, with access to the San Antonio International Airport.The freeway ends at Loop 1604, and US 281 continues through Bexar County as a superstreet.