Route 42 was originally designated in 1927 to run along the Black Horse Pike between Ferry Avenue in Camden and the present US 40/US 322 split in the McKee City section of Hamilton Township, Atlantic County.

Construction work has commenced on a project known as the "I-295/I-76/Route 42 Direct Connection," which is reconstructing the dangerous and congested Route 42/I-295/I-76 interchange in Bellmawr.

Route 42 begins at an intersection with US 322 and CR 536 Spur in Monroe Township, Gloucester County, where it heads to the north on the Black Horse Pike.

[1] Route 42 crosses the Big Timber Creek into Runnemede, Camden County, where it passes over the New Jersey Turnpike without an interchange.

[6] Snow removal, litter control, and landscaping of Route 42 between the end of the Atlantic City Expressway and I-295 is performed by the South Jersey Transportation Authority.

[7] In 1927, Route 42 was legislated to run along the Black Horse Pike, a road that traces its origins back to 1855.

[12] The North–South Freeway portion of Route 42 was originally planned as a parkway in 1932 that would run from the Ben Franklin Bridge in Camden to Atlantic City; however, this proposal never materialized.

[13] In the late 1940s, the North–South Freeway was proposed by the New Jersey State Highway Department to run from the Ben Franklin Bridge to Turnersville.

[18] In 2000, the interchanges with Route 41 and CR 544 in Deptford were rebuilt at a cost of $13 million to improve commuter travel the area.

[19] In October 2003, the New Jersey Department of Transportation (NJDOT) installed exit tabs along the freeway portion of Route 42.

[27] However, delays in construction, including the collapse of a retaining wall on March 25, 2021, pushed the expected completion date to 2028.

[28] On May 12, 2009, New Jersey Governor Jon S. Corzine and the Delaware River Port Authority, the agency which manages the PATCO Speedline, announced plans for a Camden-Philadelphia BRT (bus rapid transit system) along the Route 42 freeway and the adjacent Route 55 freeway as part of a comprehensive transportation plan for South Jersey[29] that would include a diesel light rail line called the Glassboro–Camden Line between Camden and Glassboro, improvements to NJ Transit's Atlantic City Line, and enhanced connections to the Atlantic City International Airport.