This is a nice little ride down the historic railroad trail to the Hoover Dam. The GPS is a little misleading because of the tunnels, bit it is very difficult to get lost when you're riding the trail. It is level with very little elevation change the whole way. Parking is available at the top and the bottom.
The trail is an old railroad bed that is very flat and well-maintained. It passes through several tunnels that are very large. It is a multi-use trail often traversed by hikers and bikers. Horses might be allowed too, although I've never seen them.
For more information, visit the Historic Railroad Trail webpage