and a spur connects a state highway to a Farm to Market Road or other lower rated road. Many loops are either bypasses around significant portions of populated areas or older bypassed state or national highways. One loop—around Houston—is labeled Beltway 8. The first loops and spurs were defined in 1939; prior to that, the roadways had been suffixed segments of the main state highways of which they branched. Business routes Business Interstate Highway, U.S. Highway, State Highway and Farm to Market Road shields Business routes are assigned to many old alignments of Interstate Highways, U.S. Highways, State Highways and Farm to Market Roads that have been bypassed. In addition to the numerical designation, a unique lettered suffix is assigned to each business route along the highway—for instance, Business Interstate Highway 40-D and Business Farm to Market Road 1960-A. (Not all routes start from A, and letters are sometimes skipped.) These letters are included on the sign in small print below the number. The sign specifications for business Interstate highways do not include the letter, but it has been added to many signs. Prior to 1991, business routes were assigned loop or spur numbers, but signed as business routes (with a BUSINESS plate above the shield for the main route). In 1991, all the business routes were assigned official designations, and their former loop and spur numbers were eliminated. Farm to Market Roads Farm to Market and Ranch to Market Road shields Farm to Market Roads generally exist in rural areas. After the city or county acquires right-of-way, TxDOT builds and maintains the road. A number of these roads, generally west of US 281, are designated Ranch to Market Roads, and one—Ranch Road 1—is simply a Ranch Road, serving the LBJ Ranch. Farm to Market Roads were first designated in 1941 and Ranch to Market Roads in 1942. A number of Farm to Market Roads in urban areas were re-designated in 1995 as urban roads but, amid much controversy, the markers were not changed. Park and Recreational Roads Park Road and Recreational Road shields Park Roads and Recreational Roads serve state or national parks and "recognized recreational areas"; the first ones were defined in 1937 and 1970 respectively. All roads in state parks are maintained by TxDOT, but are generally not numbered. Toll roads Toll Interstate Highway, U.S. Highway and state highway shields One characteristic of the highways in Texas