I-83 runs from Downtown Baltimore north to I-695 near the northern suburb of Timonium on the Jones Falls Expressway before forming a concurrency with I-695.

The route runs along the southern and eastern portion of the Capital Beltway that encircles Harrisburg before reaching its northern terminus.

President Street continues south along the eastern edge of the central business district (CBD) to terminate at a traffic circle in Inner Harbor East.

Running northwest out of the city center, the JFX is paralleled by its namesake river, the Jones Falls, on one side, and the Maryland Transit Administration's Baltimore Light RailLink line on the other.

Washington Pediatric Hospital, Mount Saint Agnes College, and Jones Falls Park, the route skirts the edge of Lake Roland before interchanging with Ruxton Road just south of I-695 (Baltimore Beltway).

At the beltway, I-83 leaves the JFX and joins I-695 for a distance of 1.4 miles (2.3 km), where it separates from the latter route to continue onward into northern Maryland.

Meanwhile, the JFX continues for another 0.5 miles (0.80 km) in a four-lane divided format before terminating at an at-grade intersection with MD 25 (Falls Road).

[3] I-83 enters Pennsylvania, crossing the Mason–Dixon line and passing to the east of Shrewsbury as it runs due north toward York.

Near Pennsylvania Route 462 (PA 462), the Lincoln Highway, the Interstate turns west for a short distance, then north again to an interchange with US 30.

[citation needed] It maintains this name as it passes to the south and west of Valley Green, continuing north toward Harrisburg.

Rose Avenue (PA 124) interchange took place from 2015 to 2022 in anticipation of a future widening of I-83 around the east and north sides of the city.

[10][11][12] On October 23, 2023, work began on a project that will reconstruct the section of I-83 in Dauphin County, Pennsylvania, from the John Harris Bridge over the Susquehanna River to the Eisenhower Interchange with I-283 and US 322.

[citation needed] The JFX follows the path of the Jones Falls River, a natural corridor that divided the city into eastern and western segments.

In this plan, the JFX would continue south along its present alignment then turn east and pass through the Fell's Point neighborhood on a six-lane elevated viaduct, before continuing east along Boston Street to junction I-95 (which was also rerouted to its current alignment) north of the Fort McHenry Tunnel.

In the mid-1970s, this plan was modified due to fears that the viaduct would result in destruction of the Fell's Point area, which contains many historic properties.

By 1983, the route extended all the way to Pleasant Street, with a dead-end bridge stub indicating plans to continue south along the 3-A alignment to I-95.

In September 1982, however, the segment of the JFX between Pleasant Street and I-95, a distance of 4.4 miles (7.1 km), was officially withdrawn from the Interstate Highway System.

[21] The federal funding planned to be used for the I-83 extension was instead cross-transferred to other highway projects; routes that may have benefited[original research?]

As Congress worked toward reauthorization of the Surface Transportation and Uniform Relocation Assistance Act, the Greater Lynchburg Chamber of Commerce and other groups in Virginia wanted I-83 extended southward to provide bypasses for Charlottesville, Lynchburg, and Danville, and to link those cities to Greensboro, North Carolina.

By June 1991, Robert LaLone, director of programs for the Lynchburg Chamber, admitted that an Interstate was unlikely, but upgrading US 29, with bypasses included, is more likely.

The farthest north that I-83 could be extended currently would be Benvenue, Pennsylvania, on a bridge over the Susquehanna River, where a recently built freeway section of US 22/US 322 (Dauphin Bypass) downgrades to an undivided four-lane road.

Recently, however, the Central Susquehanna Valley Thruway, a 10-mile (16 km) freeway project along the proposed corridor near Shamokin Dam, Pennsylvania, has been approved and is under construction as of 2016,[23][24] with the first section opening in 2022.

[25] In 2005, Walter Sondheim, a prominent Baltimore city planner unveiled a proposal to tear down the elevated portion of the JFX that leads into downtown.

City officials have since offered tentative support for the idea, though it is unlikely that any action will be taken until about 2020, when the current elevated structure will need an overhaul if it is to remain in use.

On May 17, 2009, The Baltimore Sun revealed a plan by Rummel, Klepper & Kahl LLP, to tear down a mile (1.6 km) of the JFX to create an urban boulevard that would help connect downtown to the east side of the city and the Johns Hopkins Hospital.