Interstate 12

Interstate 12
Interstate 12
Republic of West Florida Parkway
	I-12 highlighted in red
Route information
	Maintained by Louisiana DOTD
Length	85.59 mi (137.74 km)
Existed	1967–present
NHS	Entire route
Major junctions
West end	I-10 in Baton Rouge
	US 61 in Baton Rouge; I-55 in Hammond; US 190 between Covington and Mandeville; US 11 in Slidell;
East end	I-10 / I-59 in Slidell
Location
Country	United States
State	Louisiana
Parishes	East Baton Rouge, Livingston, Tangipahoa, St. Tammany
Highway system
	Interstate Highway System; Main; Auxiliary; Suffixed; Business; Future; Louisiana State Highway System; Interstate; US; State; Scenic;

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.

[FHWA-1] 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.

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