Wyoming Highway 320 (WYO 320) is a 12.33-mile-long (19.84 km) north–south state highway in central Platte County, Wyoming that connects Interstate 25 Business (I-25 Bus.)

Wyoming Highway 320 begins its south end at I-25 Business/US 87 Business (9th Street/Swanson Road) in Wheatland.

From here WYO 320 heads north, intersecting East Laramie River Road at 4.6 miles (7.4 km), which can take you west to I-25 (exit 84).

WYO 320 lasted until 1954, when Wyoming Highway 789 was commissioned, thereby replacing it.

Additionally, The highway that currently carries Wyoming Highway 320 was originally part of US 87 and before that US 185 (US 185 between Cheyenne and Casper was decommissioned and replaced with US 87 in 1936)[4] Between 1956 and the 1980s, as more of Interstate 25 was completed, the original routing of US 87 was recommissioned on the Interstate 25 freeway.