Topock (Mojave: Tuupak) is a small unincorporated community in Mohave County, Arizona. Topock has a ZIP Code of 86436; in 2000, the population of the 86436 ZCTA was 1,790.It lies between Bullhead City and Lake Havasu City and southeast of Needles, California, on the California–Arizona border.Topock is known for being a boating town as well as being home to the Old Trails Arch Bridge which used to be the old Route 66 bridge featured in the film The Grapes of Wrath.