U.S. Highway 11 (US 11) is a part of the United States Numbered Highway System that spans from New Orleans, Louisiana, to Rouses Point, New York. Within the state of Louisiana, the highway travels from the national southern terminus at US 90 in New Orleans to the Mississippi state line south of Picayune.

From New Orleans East, US 11 crosses Lake Pontchartrain on the nearly Maestri Bridge. The route parallels Interstate 10 (I-10) into Slidell, serving as that city's major north–south arterial. After crossing I-12, US 11 parallels I-59 to the town of Pearl River, at which point the two highways proceed concurrently across the state line.

The portion of US 11 between Slidell and Pearl River was once part of the Old Spanish Trail, an early auto trail that largely became the route of US 90 when the U.S. Numbered Highway System was implemented in 1926. US 11 originally terminated in Mississippi just northwest of what is now the Stennis Space Center. In 1937, US 90 was relocated onto a new route bypassing Slidell and Pearl River, significantly reducing the distance between New Orleans and the Mississippi Gulf Coast. US 11 was extended into Louisiana two years later over the former alignment of US 90, and the two routes were cosigned into Downtown New Orleans. This concurrency was discontinued in 1951 with US 11 being cut back to its current southern terminus at US 90 in New Orleans East.

Until the construction of the Interstate Highway System in the area during the late 1950s to mid-1960s, US 11 was one of two major routes eastward out of New Orleans, the other being US 90. Both still serve as important alternate routes to I-10 when hurricanes threaten the area, as was perhaps most evident when, in August 2005, Hurricane Katrina heavily damaged the nearby I-10 Twin Span Bridge over Lake Pontchartrain, rendering the crossing completely impassable for over six weeks. (The Maestri Bridge on US 11, constructed in 1928, had sustained only minor damage.) North of Pearl River, US 11 does not serve a similar function, however, since it was moved onto I-59 in 1965 and no longer retains a separate crossing over the various branches of the Pearl River system.

Route description New Orleans to Slidell

From the south, US 11 begins at an intersection with US 90 (Chef Menteur Highway) in New Orleans East between Michoud and Venetian Isles. It heads north along Ridgeway Boulevard as an undivided two-lane highway and travels through an area of marshland known as Irish Bayou. After , the highway reaches Point Aux Herbes, where it passes through an interchange with I-10 at exit 254. US 11 immediately continues northeast onto the Maestri Bridge, a span across Lake Pontchartrain that parallels the I-10 Twin Span Bridge.

About midway across the lake, US 11 crosses from Orleans Parish (coextensive with the city of New Orleans) into St. Tammany Parish and begins to closely follow the east side of the Norfolk Southern Railway (NS) trestle. Making landfall in North Shore, US 11 becomes known as Pontchartrain Drive and passes through the community of Eden Isle. At Oak Harbor Boulevard, the highway enters the city of Slidell and widens to accommodate a center turn lane and a second travel lane in each direction. This portion of the highway serves as a commercial corridor for the surrounding suburban area.

Slidell to Mississippi state line In Slidell, US 11 curves to the northwest and intersects Louisiana Highway 433 (LA 433; Old Spanish Trail). The center lane disappears, and the two highways run concurrent for a short distance until reaching an intersection with Front Street. Here, US 11 turns back to the northeast alongside the NS tracks while LA 433 continues straight ahead across the rail line onto Bayou Liberty Road. US 11 follows Front Street through Slidell's historic district and intersects US 190 Business (US 190 Bus.) at Fremaux Avenue, beginning a brief concurrency for several blocks to a junction with mainline US 190 at Gause Boulevard. Here, US 190 Bus. reaches its western terminus, and US 11 continues northward along Front Street, narrowing again to an undivided two-lane highway. Just beyond Indiana Avenue, US 11 crosses to the west side of the NS line via an overpass. Proceeding north for , US 11 reaches the northern limit of Slidell and enters a partial cloverleaf interchange with I-12 at exit 83, briefly widening to a divided four-lane highway. I-12 connects with Hammond to the west and a major interchange with I-10 and I-59 a short distance to the east.

Returning to two-lane capacity, US 11 continues north through the small suburb of Alton and intersects LA 1091 (Robert Boulevard), entering the town of Pearl River. later, the highway intersects LA 41 (Watts Road), which heads north toward Bogalusa. From this intersection, LA 3081 continues north along Main Street while US 11 turns southeast onto Concord Boulevard and crosses the NS line at grade. Shortly afterward, US 11 enters an interchange with I-59 at exit 3, which also marks the northern terminus of LA 1090 (Military Road). US 11 turns north to follow the onramp to I-59 and utilizes the Interstate's alignment for the remainder of its distance in Louisiana.

After , I-59/US 11 reaches exit 5A, which forms the northern terminus of LA 3081 and provides another connection to Pearl River. Immediately following this interchange, the highway crosses a bridge over the West Pearl River. Just north of the bridge is exit 5B, an interchange with a local road known as Old US 11, part of the pre-Interstate alignment that now serves Pearl River Wildlife Management Area. Exiting the Pearl River corporate limits, I-59/US 11 proceeds northward through the Honey Island Swamp and, after , reaches its final interchange, exit 11 (Pearl River Turnaround). It then crosses the main branch of the Pearl River into Mississippi at a point south of Picayune.

Route classification and data US 11 is generally classified as a rural or urban minor arterial by the Louisiana Department of Transportation and Development (DOTD). However, the section in Slidell between LA 433 and I-12 serves as an urban principal arterial. The annual average daily traffic (AADT) in 2016 ranged between about 18,900 vehicles near downtown Slidell and 3,250 in Irish Bayou, south of the Maestri Bridge. The posted speed limit is generally in rural areas, reduced to between through town.

The portion of US 11 utilizing the route of I-59 is classified as an urban Interstate through Pearl River and as a rural Interstate northward to the state line. Daily traffic volume in 2016 peaked at 29,400 vehicles, and the posted speed limit is .

History Mississippi terminuses US 11 was designated in November 1926 as one of the inaugural routes of the U.S. Numbered Highway System. The original southern terminus was located in Santa Rosa, Mississippi, at a junction with US 90, the present intersection of Mississippi Highway 607 (MS 607) and Old US 11. At that time, US 90 followed the general route of US 11 through Slidell and Pearl River. After crossing the state line into Mississippi, US 90 intersected US 11 then curved back to the south, bypassing Pearlington on the way to Bay St. Louis. This route duplicated that of the Old Spanish Trail, an auto trail designated in 1916, predating the U.S. Numbered Highway System. Since 1921, the Louisiana portion had also carried the designation of State Route 2 (SR 2), as did all of US 90 throughout the state.

In December 1935, the current route of US 90 running directly between the Fort Pike Bridge and Pearlington was opened, shortening the distance from New Orleans to the Mississippi Gulf Coast by . Once US 90 was officially shifted onto the cutoff in June 1937, US 11 was extended south to meet it at the present intersection of MS 604 and MS 607. The following year, a second cutoff was opened, placing US 90 on its current alignment between Pearlington and MS 607 west of Waveland. US 11 was again extended to intersect US 90, following MS 604 southward into Pearlington.

Extension into Louisiana In June 1939, the Louisiana Highway Commission successfully petitioned the American Association of State Highway Officials (AASHO) to have US 11 moved onto the former route of US 90 through Pearl River and Slidell and joined with US 90 to the intersection of Canal and North Broad streets in New Orleans. From the original southern terminus at Santa Rosa, US 11 then followed what is known as Old US 11, now a largely abandoned local road, to the state line where it crossed a now-demolished bridge over the Pearl River. It then continued onto Old US 11 in Louisiana, locally maintained today as part of Pearl River Wildlife Management Area, to the site of the interchange with I-59 and the current route of US 11. Continuing southwest, US 11 crossed a second demolished bridge over the West Pearl River, entering the town of Pearl River. It then followed Main Street through town, state-maintained today as part of LA 3081 and LA 3081 Spur, and rejoined the present alignment at LA 41 (Watts Road). Maps from 1939 indicate that US 11 briefly continued along the former route of US 90, turning southeast onto LA 433 to an intersection with current US 90 at the Fort Pike Bridge. Including the concurrency with US 90 into Downtown New Orleans, this routing would have represented the longest expanse of US 11 in Louisiana, totaling .

The permanent rerouting of US 11 as approved by AASHO became effective on January 1, 1940. At this time, US 11 assumed its present routing across Lake Pontchartrain via the Maestri Bridge. Originally known as the Pontchartrain Bridge (or Watson-Williams Bridge, after its backers), the nearly span was opened on February 18, 1928, and initially operated as a toll bridge. The bridge was the subject of much controversy and was a hot issue in several political campaigns during the 1920s. Louisiana Governor Oramel H. Simpson successfully advocated for free bridges to be constructed for US 90 across Chef Menteur Pass and the Rigolets, and, though the route was longer, the completion of the free spans in 1929 and 1930 led to the financial ruin of the toll bridge. In December 1938, the state of Louisiana purchased the Pontchartrain Bridge at auction, eliminated the tolls, and renamed it after New Orleans's mayor, Robert Maestri. Once US 11 was routed onto the Maestri Bridge, it continued south through Irish Bayou to its present southern terminus at US 90 and continued into town cosigned with US 90. The contemporary route of US 90 followed the current route from US 11 to Michoud; Old Gentilly Road to a point formerly known as Lee Station, where it rejoined Chef Menteur Highway; Chef Menteur Highway across the Industrial Canal and onto Gentilly Boulevard; Gentilly Boulevard to Paris Avenue; then south onto Paris and St. Bernard avenues to North Broad Street; and finally, southwest onto North Broad Street to Canal Street. This routing of US 11 in Louisiana totaled .

In May 1942, the opening of the Michoud Cutoff on Chef Menteur Highway bypassed the portion of Old Gentilly Road between Lee Station and Michoud, straightening the route of US 11-90 and eliminating two grade crossings. In 1951, the Louisiana Department of Highways eliminated several U.S. Highway concurrencies. US 51 and US 65 were removed from their concurrencies with US 61 into New Orleans, and US 11 was truncated to its present southern terminus near Irish Bayou. The number of U.S. Highway designations intersecting at Canal and North Broad streets was thus reduced from five to two (US 61 and US 90).

Interstate 59