Within the United States, each railroad operator formulates its own operating practices, subject to the regulations in Title 49 Part 236 of the Code of Federal Regulations). However, there are two major groups of railroads that have adopted common operating practices and therefore a common operating rule book. Major railroads on the East Coast have adopted the NORAC rules. Most railroads west of the Mississippi River, as well as the U.S. operations of the Canadian Pacific Railway, use the GCOR. Some large U.S. railroads, including CSX, Norfolk Southern, and the U.S. portion of the Canadian National do not subscribe to either NORAC or CROR and still use their own rule books.