Topock) 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. The crossings of the Colorado River at Topock, including the Old Trails Arch Bridge, are also featured prominently in the opening credits of the movie Easy Rider.Topock Marina located just off I-40 on Historic Route 66. Situated on the Colorado River between Needles and Lake Havasu City, the Marina is the traditional refueling point for boaters traveling between these two cities.