The entirety of the highway was once included in the '''Woodstown and Penn's Grove Turnpike''', chartered in 1852. The turnpike followed what is now
US 40 to Woodstown. The route was designated as Route 18S in 1923, running from Penns Grove southeast to
Atlantic City along what was known as the Harding Highway. US 40 was designated along the length of Route 18S, running east from a ferry dock in Penns Grove where the route crossed the
Delaware River to
Wilmington, Delaware, to continue its journey west. The entire routing of Route 18S was designated Route 48 in the
1927 renumbering of New Jersey state highways, running concurrent with US 40 its entire length. Until the
Delaware Memorial Bridge opened in 1951, a ferry connected Route 48 to
DE 48 in Wilmington. US 40 had used this ferry, but was eventually moved to a ferry that ran from
New Castle, Delaware, to
Pennsville, with US 40 being rerouted to follow present-day
Route 49, various local roads, and CR 551 to reach Route 48 and continue east along with that route. Following the completion of both the Delaware Memorial Bridge and the New Jersey Turnpike in 1951, US 40 was routed off more of Route 48 onto a new alignment, joining the route at its current eastern terminus. In the
1953 renumbering of New Jersey state highways, Route 48 was designated onto its current alignment from US 130 to US 40, with the rest of the route dropped in favor of the US 40 designation. The old alignment of Route 48 to the ferry terminal is now CR 675. == Major intersections ==