The following highways are numbered 1D:
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A spur route is a short road forming a branch from a longer, more important road such as a freeway, Interstate Highway, or motorway. A bypass or beltway is not considered a spur route as it typically reconnects with another or the same major road.
State Route 525 (SR 525) is a 30.68-mile-long (49.37 km) state highway located in Snohomish and Island counties in the western region of the U.S. state of Washington. SR 525 begins at an interchange with Interstate 5 (I-5) and I-405 in Lynnwood and travels north to SR 99 as a four-lane controlled-access freeway. From Lynnwood, the highway serves Mukilteo and becomes the terminus of SR 526 before taking its ferry route to Clinton on Whidbey Island. SR 525 traverses the island's interior as part of the Whidbey Island Scenic Byway before the designation ends at an intersection with SR 20 south of Coupeville.
State Route 20 (SR 20), also known as the North Cascades Highway, is a state highway that traverses the U.S. state of Washington. It is the state's longest highway, traveling 436 miles (702 km) across the northern areas of Washington, from U.S. Route 101 (US 101) at Discovery Bay on the Olympic Peninsula to US 2 near the Idaho state border in Newport. The highway travels across Whidbey Island, North Cascades National Park, the Okanagan Highland, the Kettle River Range, and the Selkirk Mountains. SR 20 connects several major north–south state highways, including Interstate 5 (I-5) in Burlington, US 97 through the Okanogan–Omak area, SR 21 in Republic, and US 395 from Kettle Falls to Colville.
Delaware Route 24 (DE 24) is a state highway located in Sussex County, Delaware. The route runs from Maryland Route 348 (MD 348) at the Maryland border east of Sharptown, Maryland, east to an intersection with DE 1 in Midway, between Lewes and Rehoboth Beach. Along the way, DE 24 passes through Laurel, Millsboro, and Long Neck. DE 24 intersects U.S. Route 13 (US 13) in Laurel, US 113/DE 20 and DE 30 in Millsboro, and DE 5 and DE 23 in Long Neck. DE 24 features an alternate route, DE 24 Alternate, that runs to the north of the route from US 113 in Stockley to DE 24 near Midway. DE 24 was built as a state highway throughout the 1920s, with completion of the entire route by 1931. DE 24 was assigned onto its current alignment by 1936. DE 24 Alt. was designated by 2006.
Delaware Route 23 (DE 23) is a 15.63-mile-long (25.15 km) state highway in Sussex County, Delaware. Its southern terminus is at Massey's Landing in Long Neck, near the confluence of Rehoboth Bay and Indian River Bay and its northern terminus is at the Five Points intersection in Nassau, where it ends at U.S. Route 9 (US 9)/DE 404. From the southern terminus, the route runs west through residential areas of Long Neck before heading north through rural areas with some development. DE 23 is concurrent with DE 5 between the DE 24 intersection in Long Neck and Fairmount. It is also concurrent with DE 24 Alternate between Hollymount and the DE 1D intersection in Five Points. The road was designated as part of DE 22 south of Fairmount for a short time in the 1930s, with DE 5 designated along the stretch between DE 24 and Fairmount by 1938; the remainder of the road was unnumbered. The road was fully paved by 1970. The DE 23 designation was assigned by 1994.
U.S. Route 9 (US 9) is a United States Numbered Highway in the Northeastern U.S., running from Laurel, Delaware, north to Champlain, New York. In Delaware, the route runs a southwest–northeast path through Sussex County. Even though US 9 is signed north–south for the remainder of its route, the segment in Delaware is signed east–west. The highway runs from its western terminus at US 13 in Laurel northeast to the Cape May–Lewes Ferry terminal in Lewes, where the ferry carries the route across the Delaware Bay to North Cape May, New Jersey. US 9 passes through rural areas and serves the communities of Laurel, Georgetown, and Lewes. US 9 intersects Delaware Route 20 (DE 20) in Hardscrabble, US 113 and DE 18/DE 404 in Georgetown, DE 30 in Gravel Hill, DE 5 in Harbeson, and DE 1 at the Five Points intersection in Nassau. US 9 runs concurrent with DE 404 between Georgetown and Five Points and with DE 1 between Five Points and Carpenters Corner.
Federal Highway 1D is a tolled part of the Mexico Federal Highways, paralleling Fed. 1. There are two segments, one in the state of Baja California and another in the state of Baja California Sur.
National Highway 1D, also known as Srinagar–Leh Highway, was a National Highway in the state of Jammu and Kashmir that connected Srinagar to Leh in Ladakh. The Srinagar-Leh Highway was declared as National Highway in 2006. It is now part of National Highway 1 that extends west to Uri.
King's Highway 109, or Highway 109, is a former provincial highway in Ontario. It was used on two separate, unrelated routes during the 1950s and 1960s:
Transportation in San Diego–Tijuana occurs by various means. Though, in the four cities of San Diego, Tijuana, Tecate, and Rosarito Beach, the automobile serves as most important means of transportation. The international metropolitan region maintains an intricate highway infrastructure. As a large metropolitan area in Western North America, many roadways, including Interstates, State Routes, and Mexican Federal Highways, hold a terminus in the area. These roads have grown accustomed to support the masses of the commuting populace within the international region and are constantly being expanded and/or renovated. Transportation is a crucial issue in the metropolitan area. The streets and highways of the region affect environmental health and have influence over the degree of regional connectivity. Binational discussions about coordinating public transportation across the border are currently underway. San Diego–Tijuana is the site of two major international airports and numerous regional airports. It is also the site of the Port of San Diego and miles from the nearby Port of Ensenada.
Secondary Highway 500, commonly referred to as Highway 500, was a secondary highway in the Canadian province of Ontario which was first designated in 1956. Its route was renumbered in 1964, becoming:
Secondary Highway 514, commonly referred to as Highway 514, was a secondary highway in the Canadian province of Ontario. It was used on two separate routes from the 1950s to the 1990s:
