List of highways numbered 21

For roads named A21 see ; List of A21 roads
Route 21, or Highway 21, can refer to:

International

European route E21

Austria

Wiener Außenring Autobahn

Cambodia

Canada

Alberta Highway 21

Ontario Highway 21

Czech Republic

I/21 Highway; Czech: Silnice I/21

India

National Highway 21 (India)

Iran

Road 21

Japan

Japan National Route 21

New Zealand

New Zealand State Highway 21

Turkey

, a motorway in Turkey running from Kemerhisar, Niğde Province to Tarsus, Mersin Province.

United Kingdom

British A21 (Hastings-London)

United States

U.S. Route 21

Alabama State Route 21

Arkansas Highway 21

• Arkansas Highway 21E (former)
• Arkansas Highway 21W (former)

Arkansas Highway 21E (former)

Arkansas Highway 21W (former)

California State Route 21 (former)

Colorado State Highway 21

Connecticut Route 21

Florida State Road 21

Georgia State Route 21

Alabama State Route 21

State Route 21 is a 279-mile (449 km) state highway that extends from Piedmont in Calhoun County to the Florida state line near Atmore in Escambia County. The route runs almost the entire length of the state from the northeast to the southwest. It is the longest signed state route in Alabama.

Route description

Starting at a junction with SR-9 in Piedmont, the route runs southwest through Jacksonville, Anniston, Talladega and Sylacauga. The route passes close to the Talladega Superspeedway and the Talladega National Forest. After Sylacauga the road is co-routed with U.S. Highway 231 as it heads almost directly south towards the state capital, Montgomery. Southeastroads.com gives this opinion on the part of the highway through Montgomery:

The highway is co-routed with U.S. Highways 82 and 80 around the Montgomery city center, then diverges southwest of the city. The route proceeds through Oak Hill and Beatrice to Monroeville in Monroe County, and is co-routed with SR-47 for part of this section. The route then runs continued southwest through Frisco City and Atmore to the Florida state border, where the road becomes State Road 97. The route is paved throughout and often multi-lane. Counties traversed by the route include Calhoun, Talladega, Coosa, Elmore, Montgomery, Lowndes, Wilcox, Monroe and Escambia.

Interstate 680 (California)

Interstate 680 (I-680) is a north–south Interstate Highway in Northern California. It curves around the eastern cities of the San Francisco Bay Area from San Jose to Interstate 80 at Fairfield, bypassing cities along the eastern shore of San Francisco Bay such as Oakland and Richmond while serving others more inland such as Pleasanton and Concord.

Built in the 1920s and designated in 1955, I-680 begins at a junction with I-280 and US 101 (Bayshore Freeway), and heads northeast and north-northwest through the northeast part of San Jose. After passing SR 237 in Milpitas and SR 262 in Fremont, I-680 abruptly turns northeast (where a connection to a SR 238 freeway was planned) and enters the hills and valleys of the California Coast Ranges. The highway crosses over Mission Pass, also known as the Sunol Grade, and descends into the Sunol Valley, where it meets SR 84 near Sunol. From Sunol, I-680 again heads north-northwesterly through valleys, including the San Ramon Valley, along the Calaveras Fault. Junctions along this portion include I-580 in Dublin and SR 24 in Walnut Creek. Beyond the latter interchange, a three-way directional junction with the SR 24 freeway west to Oakland, I-680 heads north into Pleasant Hill, where SR 242 splits and I-680 again heads northwesterly. After the junction with SR 4 in Martinez, the highway crosses the Carquinez Strait on the Benicia-Martinez Bridge, immediately meeting the east end of I-780 on the Benicia end. The remainder of I-680, from Benicia to I-80 at Fairfield, lies between a hilly area to the west representing the southwestern tip of the Vaca Mountains, and a marshy area (along the Suisun Bay and Cordelia Slough) to the east.