In the early days, people could cross the river at the rapids on horseback, on foot, or by wagon and buggy.

King would use the rock to determine the amount of cargo he could carry or if he could run the ferry at all.

After steam navigation was established on the river the steamer pilots would use the rock to determine if they could continue past the rapids.

This put an end to water transportation on this part of the river, and the usefulness of the rock.

This article about a property in Linn County, Iowa on the National Register of Historic Places is a stub.