Louisiana Road Network

By | October 13, 2022

Louisiana’s Interstate Highway Network.

Louisiana has a dense network of roads. Several Interstate Highways traverse the state, and a significant number of US Highways. The network of main roads is supplemented by state highways that often have a secondary importance. Formidable obstacles to traffic are the Mississippi River and its delta. The coastal strip therefore only has a limited number of roads, and it is also not possible anywhere to drive long stretches parallel to the coast. A large number of long bridges have been built in the Mississippi River delta.

Road management

The state highway authority is the Louisiana Department of Transportation and Development (DOTD). Due to the many waterways in the state, the DOTD also manages many bridges, canals, dams, flood plains, ports, and airports. The current DOTD has been in existence since 1976, but has its origins in the Louisiana Highway Commission that was established in 1921. Louisiana controls a disproportionately large share of the road network with a local function. DOTD has a Road Transfer Program, whereby roads are voluntarily transferred to the local authorities that do not fulfill an important function in the network of state highways.

  • Bittranslators: State overview of Louisiana, including geography, economy, population and history as well as introduction to major cities of Louisiana.

Interstate Highways

Several major routes of the system of Interstate Highways cross the state. Interstate 10 is the main link in the south of the state, running east-west from the Texas border through several larger cities, including the capital Baton Rouge and the largest city New Orleans. However, for through traffic, the route through New Orleans is a detour, so Interstate 12 forms a bypass between Baton Rouge and Slidell that is shorter than I-10. Through northern Louisiana, Interstate 20 is the through route for east-west traffic and passes through Shreveport.

Interstate 49 is the state ‘s main north-south route, connecting the coastal region from Lafayette with Alexandria, Shreveport, and Arkansas to the north. Interstate 55 begins just west of New Orleans and heads north into Mississippi. Interstate 59 begins at Slidell and runs northeast to Mississippi.

In addition, there are some auxiliary routes of the Interstate Highways, in the urban areas. Interstate 110 forms a north-south route through the capital city of Baton Rouge, while Interstate 210 forms the bypass of Lake Charles. Interstate 220 forms the bypass of Shreveport in the north of the state. Interstate 310 and Interstate 510 form spurs from I-10 west and east of New Orleans, while Interstate 610 forms a bypass of downtown New Orleans.

  • Deluxesurveillance: Nickname of Louisiana as The Pelican State. Also covers geography, history, economy, politics and administration of the state.

US Highways

Several US Highways cross the state. Some of these run parallel to Interstate Highways, such as US 11, US 51, and US 61. US 63 and US 65 are minor north-south routes in the north of the state. For a long time, US 71 had great importance for traffic within Louisiana, but was later replaced by I-49. US 79 runs parallel to I-20 in the northwest of the state. US 80 even runs completely parallel or over I-20. US 84 forms a somewhat secondary east-west route through the northern half of the state. Pass the US 90 is a really important connection, although it follows I-10 in the west, it forms a crucial connection between Lafayette and New Orleans and is partly designed as a freeway and elsewhere as a 2×2 divided highway. The section between Lafayette and New Orleans is planned to become part of I-49.

US Highways with a three-digit number more often run a greater distance from Interstate Highways, but in many cases have a secondary character. The US 190 is still mainly equipped with 2×2 lanes.

State Highways

The John James Audubon Bridge (LA-10) over the Mississippi River.

Since most US Highways already have a secondary role in Louisiana, this applies even more to the state highways. Along the Mississippi River is a dense network of state highways, parts of which have also been expanded with 2×2 lanes. The network of state highways is more than 26,000 kilometers long. An important upgrade project is Transportation Infrastructure Model for Economic Development or TIMED in which 862 kilometers of state highway spread over 11 corridors will be widened into a 2×2 divided highway. This project will cost nearly $5 billion and is being implemented in phases. TIMED was approved in 1989 and was estimated to be ready in 2031 in 2002, but was largely completed by 2014.

State highways have a number from 1 to 3282, the state is one of the few that gives state highways four-digit numbers. Quite a large number of state highways have been scrapped over the years. State Highways are commonly referred to as “Louisiana Highway XX” or “LA XX.” Road numbering was introduced in 1921 and the network was renumbered in 1955. In the 1930s, many new state highways were added to the network, with the result that Louisiana has an extraordinarily extensive network of state highways, disproportionate to its geographic size or population. The state operates many roads in Louisiana that would have been a county road in other states.

Originally State Highways in Louisiana were signposted with a green and white shield. In 2008 they switched to a similar shield in black and white. Another difference is that the 2008 version no longer has a frame. The road number plate is in the shape of the state of Louisiana with the number in it, including the abbreviation ‘LA’. Road numbers can have up to 4 digits. State Highway 1 is Louisiana’s longest road at 695 miles.

Parish Roads

Louisiana has no counties, but parishes. Therefore, it is a parish road and not a county road. Most are very secondary in character due to the extensive network of state highways. Only a very small part is signposted.

Toll roads

There are no regular toll roads in Louisiana. However, there are two long bridges on which tolls have to be paid, the Lake Pontchartrain Causeway and the Highway 1 elevated road. Louisiana’s electronic toll system is the GeauxPass, but cannot be used on the Lake Pontchartrain Causeway, so the transponder is barely used. The primary purpose of the GeauxPass was electronic toll collection on the Crescent City Connection, but tolls on this bridge were discontinued in 2013.


The first roads and bridges

The Huey P. Long Bridge over the Mississippi River in Metairie.

Louisiana’s infrastructure was developed quite early in rural areas due to the many cotton plantations. Louisiana’s state highways were first numbered in 1921, assigning 98 routes, increasing to 490 routes by 1929. The greatest obstacle to road traffic was the Mississippi River, and its delta in the south of the state. New Orleans was especially difficult to get to by road. Originally there were two main roads to New Orleans, the US 51 to Hammond and the US 61 to Baton Rouge. US 90 was the western outcrop. New Orleans could not be reached from the east, however, one had to make a detour around the Lake Pontchartrain. This improved in the late 1920s, the Maestri Bridge opened in 1928 (US 11) and in 1929 the Chef Menteur Bridge (US 90) opened, providing New Orleans with two more connections from the east in a short time. The first road bridge across Louisiana’s southern Mississippi River was the Huey P. Long Bridge in 1935, just west of New Orleans. In 1940 the eponymous Huey P. Long Bridge opened in Baton Rouge.

Expansion of the road network in the 1930s

By 1930, Louisiana already had an extensive network of paved roads. Nearly US Highways were already paved (except US 84 west of the Red River) and several state highways were already paved. Secondary roads were predominantly gravel roads. Due to the high rainfall in Louisiana, dirt roads did not last long. In the 1930s, Louisiana’s state highway network expanded dramatically, growing to 1,325 routes by 1930 and more than 3,000 routes by the late 1930s.

After the second World War

In the 1940s the road network was expanded little further, a second wave of road construction followed in the 1950s. Nearly all state highways of any connecting importance were asphalted at that time. Large bridges were also built. The Lake Pontchartrain Causeway opened in 1956 and the Crescent City Connection in New Orleans opened in 1958.

From 1956 it was built on the first Interstate Highways. Construction did not start very quickly in Louisiana, by 1960 only three short stretches had opened, two stretches of I-20 in the north of the state (Minden bypass and Ruston to Calhoun) and a short stretch of I-55 along ponchatoula. No part of I-10 had been opened yet. In addition, there was a large area with no roads between Lafayette and Baton Rouge. This swamp area was very inaccessible and was a large area with no roads. Traffic from Lafayette to Baton Rouge had to travel via US 167 and US 190, via Opelousas.

In the 1950s, the first roads to a 2×2 divided highway were widened. The most important was US 61 between New Orleans and Baton Rouge, portions of US 90 west and east of New Orleans, and US 190 between Krotz Springs and Baton Rouge. Elsewhere, four-lane out-of-town roads were rare, in 1960 the only stretch of 2×2 US Highway in the north of the state was US 79/80 from Shreveport to Minden.

Renumbering from 1955

In 1955, the Louisiana state highway network was completely renumbered. There were also proposals to transfer a significant portion of the minor roads to the local governments (parishes and municipalities) but this was ultimately not implemented, with the result that Louisiana operates a huge network of state highways. Until 1955, numbers were randomly assigned and did not constitute a logical system. With the 1955 renumbering, roads were divided into three classes; A (primary routes), B (secondary routes) and C (farm-to-market routes). The A routes were assigned one or two digit numbers. The B routes were numbered below 300 and other roads were given a three or four digit number. Odd numbers followed north-south routes and even numbers followed east-west routes.

Construction of the Interstate Highways

I-10 west of New Orleans.

Construction of the Interstate Highways accelerated from 1960. The Interstate Highways planned at the time were largely opened in the 1960s and early 1970s. Important for east-west traffic was the construction of the Atchafalaya Bridge west of Baton Rouge, a 29-kilometer-long bridge over the Atchafalaya Swamp. This was the first road link through this area and opened to traffic in 1973. The New Orleans and Baton Rouge urban highway network was also completed during that time.

In 1975, there were only a few missing links in the originally planned network of Interstate Highways. A short stretch of I-10 between Baton Rouge and New Orleans, completed in 1977, was missing, as well as a fairly long stretch of I-12 between Hammond and Slidell. In 1979, the missing section of I-55 between Hammond and New Orleans, the nearly 37-mile Manchac Swamp Bridge, opened. In northern Louisiana, the easternmost portion of I-20 between Tallulah and Vicksburg, which opened in the second half of the 1970s, was missing.

Interstate 49 was not part of the original Interstate Highways plan. I-45 between Houston and Dallas was the western north-south route and I-55 between New Orleans and Memphis was the eastern north-south route, nothing in between was originally planned, so north and south Louisiana was not connected by highway. Alexandria was the largest city in Louisiana without a connection to the Interstate Highways. There were plans for a toll road in the 1950sfrom Lafayette to Shreveport, but this was ultimately not carried out. Construction of I-49 was approved in the 1970s, and the highway was subsequently opened in stages between 1984 and 1996 between Lafayette and Shreveport. I-49 was planned at the time as a route that would run only in Louisiana. It was later decided to extend I-49 north to Kansas City. Most of the section from Shreveport to the Arkansas border opened in 2014.

Hurricane Katrina

In August 2005, Hurricane Katrina hit Louisiana, causing more than $100 billion in damage, mostly in New Orleans, but also along the coast of Louisiana and Mississippi. New Orleans was flooded for a long time because many flood defenses failed. Roads in the Mississippi Delta were flooded and partially damaged. The elevated highways in New Orleans were often the only accessible roads. The I-10 Twin Span Bridge over Lake Pontchartrain east of New Orleans was severely damaged. However, the nearby Maestri Bridge was barely damaged, allowing traffic to resume quickly from the east. The I-10 Twin Span Bridge was completely replaced by a modern 2×3 lane bridge between 2006 and 2011.

Recent developments

State Highway 1 is critical to the oil industry as it is the only road to Port Fourchon, from which much of the oil and gas industry in the Gulf of Mexico is supplied. However, Highway 1 is slowly sinking and is regularly underwater during storm surges. Because the road will eventually be permanently under water over a long stretch, the Highway 1 elevated road has been constructed, the first phase of which was 13 kilometers opened in 2009. In 2013, the Crescent City Connection in New Orleans became toll-free.


The focus is on the construction of two Interstate Highways, I-49 and I-69. Interstate 49 will eventually run from New Orleans to the Arkansas border. The section between New Orleans and Lafayette is already part freeway that is part of US 90. In Lafayette, the freeway is to be built through the city. It is also planned to run I-49 through Shreveport.

Interstate 69 is to run through northwestern Louisiana, south and east of Shreveport. This is part of the corridor from Mexico to Canada. The project has a higher priority in Texas than in Louisiana, but the section from the Texas border to I-20 east of Shreveport is being actively studied. State Highway 3132 (Inner Loop Expressway) in Shreveport also needs to be extended to the new I-69.

In southern Louisiana, Highway 1 must be protected against rising seawater and falling soil. This is done by constructing the Highway 1 elevated road, which should eventually be 29 kilometers long.

Baton Rouge is thinking about a ring highway. The city is currently overly dependent on I-10’s bridge over the Mississippi River, a major bottleneck. However, there are no plans for major road projects in New Orleans.

Louisiana Road Network