The Chicago, Rock Island and Pacific Railroad (CRI&P RR) (reporting marks RI, ROCK) was a Class I railroad in the United States. It was also known as the Rock Island Line, or, in its final years, The Rock.  Its ancestor, the Rock Island and La Salle Railroad Company, was incorporated in Illinois on February 27, 1847, and an amended charter was approved on February 7, 1851, as the Chicago and Rock Island Railroad. Construction began October 1, 1851, in Chicago, and the first train was operated on October 10, 1852, between Chicago and Joliet. Construction continued on through La Salle, and Rock Island was reached on February 22, 1854, becoming the first railroad to connect Chicago with the Mississippi River.