Interstate 175 (I-175) in St. Petersburg, Florida, also known as South Bay Drive, is a 1.3-mile-long spur route from Interstate 275 into downtown. It is also designated as the unsigned State Road 594. There is a sibling segment of freeway nearby designated as I-375.
The interstate begins at I-275 with Tropicana Field on the northeast side of the interchange, going east into downtown St. Petersburg, passing through eastbound exits with 9th Street South/8th Street South and 6th Street South before the interstate ends at 5th Avenue South next to an at-grade intersection with 4th Street South. Westbound, the interstate begins with a split from southbound 4th Street South just north of the 4th Street South/5th Avenue South intersection, and has no exits until the interchange with I-275. Along with its sister highway I-375, I-175 lacks exit numbers.
The freeway was originally to have been a part of the former Pinellas Belt Expressway, which would have continued from its western terminus at I-275. The Pinellas Belt Expressway was budgeted in 1974 but was cancelled in the late 1970s due to local opposition. I-175 was built between 1977 and 1980 and opened on April 23, 1980 at a cost of $5.5 million ($13.7 million in 2007 dollars).
When I-75 was relocated in the late 1970s/early 1980s, five miles (8 km) of additional interstate became available; thus, the St. Petersburg feeder sections of I-175 and neighboring I-375 were upgraded to interstate status.