High Quality Content by WIKIPEDIA articles! Interstate 19 (I-19) is an intrastate Interstate Highway located entirely within the state of Arizona. I-19 runs from Nogales, roughly 1,500 feet (460 m) from the Mexican border, to Tucson, at Interstate 10. Having a total length of just over 63 miles (101 km), I-19 is the fourth shortest primary (two-digit) Interstate in the contiguous 48 states, where only I-97, Interstate 73, and Interstate 86 in Idaho are shorter.