Back Interstate 12 German Interestatal 12 Spanish Interstate 12 Basque بزرگراه میانایالتی ۱۲ Persian Interstate 12 French Interstate 12 Hungarian Interstate 12 Italian 州間高速道路12号線 Japanese 주간고속도로 제12호선 Korean Interstatal 12 LMO
Interstate 12 | ||||
|---|---|---|---|---|
| Republic of West Florida Parkway | ||||
 I-12 highlighted in red | ||||
| Route information | ||||
| Maintained by Louisiana DOTD | ||||
| Length | 85.59 mi[1] (137.74 km) | |||
| Existed | 1967–present | |||
| NHS | Entire route | |||
| Major junctions | ||||
| West end |  I-10 in Baton Rouge | |||
| East end |  I-10 / I-59 in Slidell | |||
| Location | ||||
| Country | United States | |||
| State | Louisiana | |||
| Parishes | East Baton Rouge, Livingston, Tangipahoa, St. Tammany | |||
| Highway system | ||||
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Interstate 12 (I-12) is an intrastate Interstate Highway located entirely within the US state of Louisiana. It spans a total of 85.59 miles (137.74 km)[1] in an east–west direction from I-10 in Baton Rouge to an interchange with both I-10 and I-59 in Slidell. Along the way, it passes through the city of Hammond, where it intersects I-55 and US Route 51 (US 51). It also serves the cities of Ponchatoula and Denham Springs, as well as the St. Tammany Parish cities of Covington and Mandeville.
I-12 parallels the older US 190 corridor and traverses the north shore of Lake Pontchartrain in the southeastern portion of the state. The Interstate's length is short for a mainline Interstate and is comparable with the country's longest auxiliary Interstates. It is one of the shortest mainline Interstates to terminate at the same route (I-10) at either end. Apart from serving the various communities of the North Shore, I-12 acts as a long bypass of New Orleans and is heavily used as a shortcut for through traffic on I-10. While I-10 curves to the south to pass through the city limits, I-12 takes a more direct alignment, reducing the distance between Baton Rouge and Slidell by about 22 miles (35 km).
In 1993, the Louisiana State Legislature designated I-12 as the Republic of West Florida Parkway. In 2003, signs identifying the highway's official name and bearing the flag of the Republic of West Florida were erected by the Louisiana Department of Transportation and Development (DOTD) in order to highlight the unique history of Louisiana's Florida Parishes.
Louisiana is in the process of widening I-12 to three lanes in each direction in locations such as Covington and Mandeville where the Interstate is still two lanes in each direction.
- ^ a b Starks, Edward (January 27, 2022). "Table 1: Main Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways". FHWA Route Log and Finder List. Federal Highway Administration. Retrieved March 20, 2023.