|Length:||52.50 mi (84.49 km)|
|West end:||I‑20 / I‑59 / I‑459 / US-11 south of Bessemer|
| SR-269 at Sylvan Springs
US-78 at Adamsville
I‑65 at Morris
US-31 at Morris
SR-79 at Pinson
SR-75 at Pinson
|East end:||I‑59 near Argo|
Corridor X-1 or the Birmingham Northern Beltline is a proposed 52.5-mile (84.5 km) northern by-pass route around Birmingham, Alabama through northern and western Jefferson County that is projected to be completed by 2048. Along with the existing I-459, the Northern Beltline would complete the bypass loop of central Birmingham for all interstate traffic. The project's budget is $5.445 billion; upon completion, the Northern Beltline will be the most expensive road in Alabama's history and among the most expensive per-mile ever built in the United States.
Current plans for the route have it connecting at I-459's current southern terminus in Bessemer with I-59 at approximately mile marker 147 to the northeast of Trussville near Argo. Additional studies are underway to determine the economic feasibility to continue the route from its proposed northern terminus to I-20 in the Leeds/Moody area.
The route has been designated as the Appalachian Regional Commission, High Priority Corridor X-1, State Route 959 and Interstate 422.
As early as the 1960s, the prospect of a complete beltway encircling Birmingham was envisioned. Although the proposal was initially dropped from the original Interstate Highway System, the completion of Birmingham's outer beltway has been speculated since the completion of I-459 in 1985. By 1989, the first federal and local funds were earmarked for a project to study the feasibility of constructing the route.
In September 1993 the Birmingham Metropolitan Planning Organization made a $500,000 request from the Alabama Department of Transportation (ALDOT) for preliminary engineering of the beltline. Through the continued efforts of representative Spencer Bachus, in June 1995, the project was designated by the Federal Highway Administration as part of the National Highway System. As a result of this designation, the beltline would be eligible for federal transportation dollars.
In 1997, the Environmental Protection Agency (EPA) reviewed a number of potential routes for the Birmingham Northern Beltline. They submitted comments on September 8, 1997 and recommended ALDOT select a shorter, 30 mile route due to its smaller environmental impact. They also firmly recommended against the longest route, citing that the route would "disrupt streams at 14 crossings, impact over 4050 acres forested lands within the ROW, and will destroy up to 68 acres of wetlands at 114 different sites. It will also have the greatest impact on wildlife of all the alignments discussed". This is the route that ALDOT eventually selected for the Northern Beltline.
In 2000, the Northern Beltline was added to the area’s Transportation Plan, and in 2001, Senator Richard Shelby and Congressman Spencer Bachus secured $60 million to buy right of-way and do preliminary engineering for the route. In 2003, Shelby secured an additional $2 million for the continued purchasing of right-of-way. Progress continues with the purchasing of additional right-of way through the county as of 2006.
Construction started on a 1.34 mile section near Pinson on February 24, 2014 which will connect Alabama State Route 75 and Alabama State Route 79.  This section is budgeted to cost $46 million and will be completed by fall 2016. 
The construction of the Northern Beltline has raised serious questions from local communities, taxpayers, and local conservation groups. Lawsuits filed in 2011 and 2013 to block construction of the beltline by environmental groups are currently pending in federal court. The groups cited the project's environmental and economic impact in their filing. Although the groups' request for preliminary injunction to stop construction was blocked in January 2014, a final judgement has not been made yet on the case.
The Northern Beltline will cross Black Warrior and Cahaba river tributaries in 90 places (including two major sources of drinking water). It will also destroy 35 wetlands and 3,078 football fields of forests once constructed. In return, the beltline will reduce traffic on other interstates in the area by 1-3%. On certain areas of I-59, the beltline is expected to increase traffic congestion.
The 52-mile long project is budgeted to cost $5.445 billion, making it the most expensive road project in Alabama history. At $104.7 million per mile, this budget also makes the Northern Beltline one of the most expensive roads per mile ever built in the United States. Notably, this price tag does not take into account the cost of extending sewer services, power lines, and other infrastructure necessary to develop the isolated region through which the beltline will be constructed. In 2010, a study estimated 69,535 jobs would be created by the beltline. However, a later study found that just 2,805 jobs would be added in the area by 2048.
Interstate 459 East (Southbound only)
Exit 5- 15th Street Road/ Bessemer (to the left of Hueytown High School)
Exit 7- Jefferson County Road 46/ Warrior River Road/ Hueytown, Concord
Exit 16- Jefferson County 77/ New Found Road
Exit 17- Jefferson County 112/ Mount Olive Road/ Gardendale
Exit 21- Jefferson County 129/ Glenwood Road
Exit 22- Jefferson County 121/ New Castle Road
Exit 23- Jefferson County 151/ Narrows Road/ Pinson
Exit 25- AL 79/ New Bradford Hwy./ Pinson
Exit 26- AL 75/ Pinson
- MacDonald, Ginny (May 26, 2009). "Corridor X/ I-65 interchange construction could begin this year". The Birmingham News.
- Roberts, Chris (September 15, 1993). "JeffCo, Shelby getting $120 million for roads." Birmingham News
- Gordon, Tom (June 10, 1995) "Northern Beltline gets federal priority." Birmingham News
- Nicholson, Gilbert (May 11, 2001). "Northern Beltline: Land rush may ensue when road's route announced this summer." Birmingham Business Journal.
- Birmingham Business Journal (September 4, 2003). "Sen. Shelby continues to bring home transportation bacon." Birmingham Business Journal.
- Corridor X-1 at Regional Planning Commission of Greater Birmingham site
- ALDOT, FHWA, Final Environmental Impact Statement Reevaluation, March 2012, Appendix L.