divided highways and 55 mph for all other highways. Many of these other class roadways also had separate day and night speed limits as well. Texas Texas is the only state that does not prescribe a different speed limit for each road type in its state or federal highway system. Texas law generally prescribes a statutory speed limit of for any rural road that is numbered by the state or federal government (United States Numbered Highways and Interstate Highways)—whether two lane, four lane, freeway, or otherwise— for roads outside an urban district that are not federal or state highways, and for streets in an urban district. The law allows raising or lowering the statutory limit only if an engineering and traffic investigation indicates that a different limit is appropriate. Texas allows a speed limit of up to to be posted on federal or state highways, city maintained roads, and toll roads, and up to on county roads. Through a separate provision, speed limits up to or can be established on certain highways. Truck speed limits Texas once had separate, systemwide truck speed limits, but they were repealed in 1999 and 2011. The truck speed limit used to be day/ night when the regular limit was higher. This speed limit did not apply to buses or to trucks transporting United States Postal Service mail. Truck speed limits disappeared when all speed limits were capped at in 1974. They reappeared with the introduction of limits in 1987. Effective September 1, 1999, Texas repealed truck speed limits on all roads except farm to market and ranch to market roads. In 2001, a bill allowing 75 mph speed limit on roads in certain counties excluded trucks, introducing a 70 mph truck speed limit on roads with a higher limit. A bill in 2005 allowing 80 mph speed limits still excluded trucks. However, truck speed limits were fully repealed in 2011. Night speed limits Before September 1, 2011, Texas had a statutory night speed limit on all roads with a higher daytime limit. In 2011, the Texas Legislature banned night speed limits effective September 1, 2011. However, as of June 2013, night speed limits (55) were retained on some county roads where the speed limit is 60 mph in Scurry County, just outside of Snyder, Texas. Environmental speed limits Texas is the first state to lower speed limits for air quality reasons, although the lowered