Wikipedia:WikiProject U.S. Roads/New Jersey/Selected article/October 2014

Route 124 is a state highway in the northern part of New Jersey in the United States that is 14.74 mi (23.72 km) long. It is the eastern section of what used to be Route 24 before that road was realigned to its current freeway alignment. The western end is at an intersection with U.S. Route 202 (US 202) and County Route 510 (CR 510) in Morristown, Morris County; the eastern end continues as County Route 603 on Springfield Avenue at the border between Maplewood and Irvington in Essex County. The route runs through suburban areas of Morris County, passing through Madison and Chatham. It interchanges with Route 24 on the border of Millburn, Essex County and Summit, Union County and serves as a frontage road for that route. Upon splitting from Route 24, Route 124 continues east through Springfield Township, Union Township, and Maplewood to its eastern terminus.

The alignment of today’s Route 124 was first designated as a part of pre-1927 Route 5 in 1916, a route that was to run from Delaware, Warren County to Newark. In 1927, this portion of the route became a part of Route 24, a route that was to run from Phillipsburg to Newark. A freeway, which is the current alignment of Route 24, was proposed for this portion of the route in the 1950s that was approved in 1960. Route 24 was moved to the new freeway between the John F. Kennedy Parkway on the Millburn/Summit border and Interstate 78 (I-78) in 1972, with Route 124 being designated along the former alignment of Route 24 east of this point. In 1992, the Route 24 freeway was completed between I-287 in Hanover Township and the John F. Kennedy Parkway. As a result, Route 124 was extended west along the former Route 24 to U.S. Route 202 in Morristown.