Interstate 12 is an intrastate Interstate Highway located entirely within the state of Louisiana

Louisiana

Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

. I-12 starts in Baton Rouge

Baton Rouge, Louisiana

Baton Rouge is the capital of the U.S. state of Louisiana. It is located in East Baton Rouge Parish and is the second-largest city in the state.Baton Rouge is a major industrial, petrochemical, medical, and research center of the American South...

 at Interstate 10

Interstate 10

Interstate 10 is the fourth-longest Interstate Highway in the United States, after I-90, I-80, and I-40. It is the southernmost east–west, coast-to-coast Interstate Highway, although I-4 and I-8 are further south. It stretches from the Pacific Ocean at State Route 1 in Santa Monica,...

, and travels along the North Shore of Lake Pontchartrain

Lake Pontchartrain

Lake Pontchartrain is a brackish estuary located in southeastern Louisiana. It is the second-largest inland saltwater body of water in the United States, after the Great Salt Lake in Utah, and the largest lake in Louisiana. As an estuary, Pontchartrain is not a true lake.It covers an area of with...

 before ending at the intersection of Interstate 10

Interstate 10

Interstate 10 is the fourth-longest Interstate Highway in the United States, after I-90, I-80, and I-40. It is the southernmost east–west, coast-to-coast Interstate Highway, although I-4 and I-8 are further south. It stretches from the Pacific Ocean at State Route 1 in Santa Monica,...

 and Interstate 59

Interstate 59

Interstate 59 is an Interstate Highway in the southern United States. Its southern terminus is near Slidell, Louisiana, a suburb of New Orleans, at an intersection with Interstate 10 and Interstate 12, its northern terminus is at Wildwood, Georgia, at an intersection with Interstate 24.The road's...

 near Slidell

Slidell, Louisiana

Slidell is a city situated on the northeast shore of Lake Pontchartrain in St. Tammany Parish, Louisiana, United States. The population was 25,695 at the 2000 census. The Greater Slidell Community has a population of about 90,000...

. I-12 is only 85 miles long between Baton Rouge and Slidell, while I-10 takes 108 miles to travel between the same two points, so I-12 is heavily-used as a shortcut for through traffic on I-10. I-12 is six lanes from its western terminus until Exit 7 (O'Neal Lane) at which point it becomes a four-lane highway to its eastern terminus.

In 1993, the state legislature renamed Interstate 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

Louisiana Department of Transportation and Development

The Louisiana Department of Transportation and Development is a state government organization in charge of maintaining public transportation, roadways, bridges, canals, select levees, floodplain management, port facilities, commercial vehicles, and aviation which includes 69 airports, in the U.S....

 in order to highlight the unique history of Louisiana's Florida Parishes

Florida Parishes

The Florida Parishes , also known as the North Shore region, are eight parishes in the southeastern part of the U.S. state of Louisiana, which were part of West Florida in the 18th and early 19th centuries. Unlike much of Louisiana, this region was not part of the Louisiana Purchase, as it had been...

.

The highway is relatively short for a mainline route at only 85 miles (136.8 km). While Interstates 19

Interstate 19

Interstate 19 is an intrastate Interstate Highway located entirely within the state of Arizona. I-19 runs from Nogales, roughly 1,500 feet from the Mexican border, to Tucson, at Interstate 10...

, 66

Interstate 66

Interstate 66 is an Interstate Highway in the eastern United States. As indicated by its even route number, it runs in an east–west direction. Its western terminus is at Middletown, Virginia, at an intersection with Interstate 81; its eastern terminus is in Washington, D.C., at an...

, 97

Interstate 97

Interstate 97 is an intrastate Interstate Highway located entirely within Anne Arundel County, Maryland, United States. It runs from Annapolis at the overlapped section of US 50, US 301, and the unsigned I-595 to Baltimore at the city's beltway...

, and the partially completed Interstate 99

Interstate 99

Interstate 99 is an intrastate Interstate Highway located in central Pennsylvania in the United States. The southern terminus of the route is at exit 146 of the Pennsylvania Turnpike north of Bedford, where the road continues south as U.S. Route 220 . The northern terminus is at...

 are all shorter, none of these has two termini with the same route, much less within the same state (I-99 will eventually extend into New York

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

). Compare the length of I-12 to that of the 73.5 miles (118.3 km) I-295

Interstate 295 (Delaware-New Jersey)

Interstate 295 in New Jersey and Delaware is an auxiliary Interstate Highway, designated as a bypass around Philadelphia, Pennsylvania. The route begins at a junction with Interstate 95 south of Wilmington, Delaware, and runs to another junction with I-95 north of Trenton, New Jersey...

 in New Jersey and Delaware, or the 72.8 miles (117.2 km) I-405

Interstate 405 (California)

Interstate 405 is a major north–south Interstate Highway in Southern California. It is a bypass of Interstate 5, running along the western areas of the Greater Los Angeles Area from Irvine in the south to near San Fernando in the north...

 in California, or even the 121 miles (194.7 km) I-495

Interstate 495 (Massachusetts)

Interstate 495 is the designation of an Interstate Highway half-beltway in Massachusetts. It was the longest auxiliary Interstate Highway of its kind—measuring 120.74 miles —until 1996, when the PA Route 9 section of the Pennsylvania Turnpike was redesignated as Interstate 476, making it about ...

 in Massachusetts, all of which are auxiliary Interstate Highways.

Route description

I-12 begins just east of downtown Baton Rouge at an interchange with I-10, with I-10 heading toward New Orleans and I-12 acting as a de-facto bypass of the New Orleans area. I-12 continues east passing through the suburbs of Baton Rouge, before transitioning into a rural interstate for the rest of its length. It makes an interchange with I-55 near Hammond. East of Hammond, the route passes near the northern shore of Lake Pontchartrain, and crosses scenic streams like the Tangipahoa River

Tangipahoa River

The Tangipahoa River originates northwest of McComb in southwest Mississippi, and runs south through Lake Tangipahoa in Percy Quin State Park before passing into southeast Louisiana. Its mouth opens into the northwest region of Lake Pontchartrain....

 south of Robert

Robert, Louisiana

Robert is an unincorporated community in Tangipahoa Parish, Louisiana, United States. It lies east of Hammond, at the intersection of US 190 and LA 445, from which it has a signed exit on Interstate 12...

, Sims Creek

Sims Creek

Sims Creek is a tributary of the Tangipahoa River in the 8th Ward of Tangipahoa Parish, Louisiana. It flows generally southeast from near Robert, and is joined about halfway down its course by its longest tributary, P-Kaw-Shun Creek, which begins north of Lorraine and flows southwest, passing...

 southeast of Goodbee

Goodbee, Louisiana

Goodbee is an unincorporated community in Saint Tammany Parish, Louisiana, United States, at the intersection of U.S. Route 190 and Louisiana Highway 1077 west of Covington. Goodbee has a signed exit on Interstate 12 to its south, at its interchange with LA 1077.Northwest of Goodbee is the start...

, and the Tchefuncte River

Tchefuncte River

The Tchefuncte River drains into Lake Pontchartrain in Louisiana in the United States. It is about long.In the 19th century it was an important commercial waterway, where building materials and other products of the North Shore of Lake Pontchartrain were loaded to be shipped across the Lake to...

 north of Madisonville

Madisonville, Louisiana

Madisonville is a town in St. Tammany Parish, Louisiana, United States. The population was 677 at the 2000 census. It is part of the New Orleans–Metairie–Kenner Metropolitan Statistical Area.-Geography:...

. I-12 ends at I-10 and the southern terminus of I-59 near Slidell.

I-12 is the only Interstate roadway that Livingston Parish uses, as it virtually slices the parish in half.

History

Interstate 12 was added to the highway system on October 17, 1957, with I-12 running from I-10 in Baton Rouge to I-59 north of Slidell. By the mid-1960s, the routes had been realigned to their current configuration, with I-12 and I-59 both ending at I-10 near Slidell.

With major damage to the I-10 Twin Span Bridge across Lake Pontchartrain

Lake Pontchartrain

Lake Pontchartrain is a brackish estuary located in southeastern Louisiana. It is the second-largest inland saltwater body of water in the United States, after the Great Salt Lake in Utah, and the largest lake in Louisiana. As an estuary, Pontchartrain is not a true lake.It covers an area of with...

 from Hurricane Katrina

Hurricane Katrina

Hurricane Katrina of the 2005 Atlantic hurricane season was a powerful Atlantic hurricane. It is the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States. Among recorded Atlantic hurricanes, it was the sixth strongest overall...

, I-12 was temporarily functioning as I-10. On October 14, 2005, the eastbound span of I-10 over Lake Pontchartrain was reopened to two-way traffic. The westbound span of I-10 reopened on January 6, 2006, with speed, weight and size restrictions, relieving I-12 of much of the congestion that was clogging it from the Lake Pontchartrain Causeway

Lake Pontchartrain Causeway

The Lake Pontchartrain Causeway, or the Causeway, consists of two parallel bridges crossing Lake Pontchartrain in southern Louisiana, United States. The longer of the two bridges is long...

 to the junction with I-10 and I-59.

Widening and Improvements

In 2009, a project broke ground to widen I-12 from the O'Neal Lane Interchange (exit 7) to the LA 447

Louisiana Highway 447

Louisiana Highway 447 is a state highway in Louisiana that serves Livingston Parish. It spans in a south to north direction. It is known locally as Walker Road North & Walker Road South .-Route description:...

 interchange in Walker, Louisiana

Walker, Louisiana

Walker is a town in Livingston Parish, Louisiana, United States. The population was 4,801 at the 2000 census. It is part of the Baton Rouge Metropolitan Statistical Area...

. The current bottleneck has traffic backed up for a few miles.

Also, in 2010, construction began at the Louisiana Highway 1088

Louisiana Highway 1088

Louisiana Highway 1088 is a state highway in Louisiana that serves St. Tammany Parish. It spans and runs from southwest to northeast.-Route description:...

 overpass in St. Tammany Parish to make it an exit. The finished project has a widened LA 1088 over I-12. This exit was created to alleviate conjestion on local roads and to create a more direct route to the newly opened Lakeshore High School.

In 2011, officials began constructing a third travel lane in each direction on I-12 from the Vincent's Bayou Bridge to the I-10/I-12/I-59 split.

Exit list

Parish	Location	# Exit number An exit number is a number assigned to a road junction, usually an exit from a freeway. It is usually marked on the same sign as the destinations of the exit, as well as a sign in the gore....	Destinations	Notes
East Baton Rouge East Baton Rouge Parish, Louisiana East Baton Rouge Parish is a parish located in the U.S. state of Louisiana. The parish seat is Baton Rouge, Louisiana's state capital. As of the 2010 census, the population was 440,171. The parish has a total area of , of which is land and is water. It is the most populous parish in the state...	Baton Rouge Baton Rouge, Louisiana Baton Rouge is the capital of the U.S. state of Louisiana. It is located in East Baton Rouge Parish and is the second-largest city in the state.Baton Rouge is a major industrial, petrochemical, medical, and research center of the American South...
		1A
		1B		No westbound exit
				Westbound exit and eastbound entrance only
		2		Alternate route to Baton Rouge Metropolitan Airport Baton Rouge Metropolitan Airport Baton Rouge Metropolitan Airport , also known as Ryan Field, is a public use airport located four nautical miles north of the central business district of Baton Rouge, a city in East Baton Rouge Parish, Louisiana, United States.... Signed as exit 2A (south) and 2B (north)
		4	Sherwood Forest Boulevard
		6	Millerville Road
		7
Livingston Livingston Parish, Louisiana Livingston Parish Is a parish located in the U.S. state of Louisiana. Its parish seat is Livingston. As of 2010, its population was 128,026....	Denham Springs Denham Springs, Louisiana Denham Springs is a city in Livingston Parish, Louisiana, United States, and part of the Baton Rouge Metropolitan Statistical Area. Downtown Denham Springs has transformed itself from hardware stores, drug stores, doctor's offices, and a single movie theater to a collection of various and varied...	10
		12
	Walker Walker, Louisiana Walker is a town in Livingston Parish, Louisiana, United States. The population was 4,801 at the 2000 census. It is part of the Baton Rouge Metropolitan Statistical Area...	15
		19	Colyell Colyell, Louisiana Colyell is an unincorporated community in Livingston Parish, Louisiana, United States. It was named for Francisco Collel, who was the commandant of Galveztown in 1779.... , Satsuma Satsuma, Louisiana Satsuma is a town in Louisiana, in the United States. It owes its origin to the very necessary US Post Office Department rule which does not permit two post offices in the same state to have the same name. Satsuma is located on US Hwy...
	Livingston Livingston, Louisiana Livingston is a town in and the parish seat of Livingston Parish, Louisiana, United States. The population was 1,342 at the 2000 census. It is part of the Baton Rouge Metropolitan Statistical Area....	22
		29
		32
Tangipahoa Tangipahoa Parish, Louisiana Tangipahoa Parish is a parish located in the U.S. state of Louisiana, one of the Florida Parishes. The parish seat is Amite City, but the major city is Hammond. As of 2006, the population was 113,137...		35	, Pumpkin Center Road, Baptist Baptist, Louisiana Baptist is an unincorporated community in Tangipahoa Parish, Louisiana, United States. Baptist is located on U.S. Route 190 west of Hammond....
		38	, Jackson Jackson, Mississippi Jackson is the capital and the most populous city of the US state of Mississippi. It is one of two county seats of Hinds County ,. The population of the city declined from 184,256 at the 2000 census to 173,514 at the 2010 census...	Signed as exits 38A (south) and 38B (north)
	Hammond Hammond, Louisiana Hammond is the largest city in Tangipahoa Parish, Louisiana, United States. The population was 20,049 at the 2009 census. It is home to Southeastern Louisiana University...	40		To Southeastern Louisiana University Southeastern Louisiana University Southeastern Louisiana University is a state-funded public university in Hammond, Louisiana, United States. It was founded in 1925 by Linus A. Sims, the principal of Hammond High School, as Hammond Junior College, located in a wing of the high school building. Sims succeeded in getting the campus...
		43
		47
St. Tammany St. Tammany Parish, Louisiana St. Tammany Parish is a parish located in the U.S. state of Louisiana, in the New Orleans–Metairie–Kenner Metropolitan Statistical Area. The parish seat is Covington....		57
		59
		60	Pinnacle Parkway, East Brewster Road
		63		Signed as exits 63A (Southbound to Mandeville & Lake Pontchartrain Causeway Lake Pontchartrain Causeway The Lake Pontchartrain Causeway, or the Causeway, consists of two parallel bridges crossing Lake Pontchartrain in southern Louisiana, United States. The longer of the two bridges is long... ) and 63B (Northbound to Covington)
		65
		66
		74
	Slidell Slidell, Louisiana Slidell is a city situated on the northeast shore of Lake Pontchartrain in St. Tammany Parish, Louisiana, United States. The population was 25,695 at the 2000 census. The Greater Slidell Community has a population of about 90,000...	80	Northshore Boulevard, Airport Road
		83
		85A
		85B	- Hattiesburg Hattiesburg, Mississippi Hattiesburg is a city in Forrest County, Mississippi, United States. The population was 44,779 at the 2000 census . It is the county seat of Forrest County...
		85C	- Bay St. Louis Bay St. Louis, Mississippi Bay Saint Louis is a city located in Hancock County, Mississippi. It is part of the Gulfport–Biloxi, Mississippi Metropolitan Statistical Area. As of the 2000 census, the city had a total population of 8,209. It is the county seat of Hancock County...