Where crushed limestone trail trail  follow the Chicago, Rock Island and Pacific Railroad, also known as Rock Island Line or The Rock?
Hoover Nature Trail: The Hoover Nature Trail (HNT) is a crushed limestone rail trail in eastern Iowa that follows the old Chicago, Rock Island and Pacific Railroad route between Burlington and Cedar Rapids. Chicago, Rock Island and Pacific Railroad: The Chicago, Rock Island and Pacific Railroad (CRI&P RW, sometimes called "Chicago, Rock Island and Pacific Railway") (reporting marks CRIP, RI, ROCK) was a Class I railroad in the United States.
The Hoover Nature Trail