An important site in the history of America is Independence Rock. This out-of-place rock was the predictor of potential success for the thousands of wagon trains that headed up the Oregon Trail. The conventional wisdom was, if you can make it to Independence Rock by the date of July 4 (Independence Day), then you have enough time to traverse the Rocky Mountain passes before the autumn storms and snow hits. If you get to the rock too late, you are SOL.
So if you are driving the exceedingly remote State Road 220 through Wyoming, make time to visit the infamous rock. There is a walkway to allow people to circumambulate the behemoth and get really close. The rock is vandalized by hundreds of 19th century travelers, carving their names and dates into the stone in archaic fonts from the old days.