Grinnell Burt would serve as the president of the newly consolidated line, as he had with the WVRR, up until his death in 1901 and would be instrumental in progressing the L&HR to become a "link in a great chain" of transportation in the northeast.

The Warwick Valley Railroad had built an extension southwest to McAfee in March 1880, and the full line opened August 14, 1882, connecting Belvidere, New Jersey, to Greycourt, New York.

For several years, the L&HR carried freight from its western connections to Greycourt where the Erie operated a branch to the car floats at Newburgh, New York.

Sensing the opportunity, the Orange County Railroad was chartered as an L&HR line on November 28, 1888, and opened the following year, extending the line northeast from Greycourt to Burnside where Trackage rights were obtained over a short piece of the New York, Ontario and Western Railway from the junction at Burnside west to the major junction at Campbell Hall.

From October 1912 until January 1916, the L&HR hosted the PRR's Federal Express passenger trains on the Poughkeepsie Bridge Route between Phillipsburg and Maybrook.

With the completion of the Hell Gate Bridge in New York City on September 9, 1917, the Federal Express resumed service via Penn Station and the New Haven Line direct.

As the L&HR was built along a length of the Great Appalachian Valley, grades were relatively mild and long flat stretches of rail made speeds of over 60 mph common.

With the exception of a short portion of double-track at Belvidere, the entire line was single-tracked with occasional passing sidings every 5–10 miles to handle the high volume of trains.

Due to this streamlined operation, trains out of Allentown ran directly to Maybrook without having to be switched or otherwise handled as almost of the freight was destined to the Poughkeepsie Bridge and New England.

With a few exceptions, there were no major online heavy industries besides the dozens of creameries and ice houses that dotted the line along its entire length.

The dairy industry was especially strong in Warren, Sussex, and Orange Counties where the L&HR serviced numerous farming communities and forwarded their products to the interchange with the Erie and Greycourt where they would then be sent to market in New York City.

The L&HR was also an important supplier of coal for these communities serving as a link to the anthracite mining regions of Pennsylvania via their connections with the DL&W and CNJ.

L&HR power upgraded in the years during and after WWI locomotives during this time were noted for their Wootten fireboxes; designed to burn the harder anthracite coal.

As a result of traffic surges from WWII, the L&HR bought their last steam locomotives from Baldwin in 1944; a trio of 4-8-2 Mountains that, due to war-time restrictions, were virtual copies of the Boston & Maine's R1d design Lehigh & Hudson River Railway Locomotive Roster; 1950 Despite having been a customer of Baldwin since 1894, when the end of steam came in December 1950, the replacements would be exclusively from ALCO.

Both sections became part of the New York, Susquehanna and Western Railway's (NYS&W) Southern Division, and the trackage was subsequently upgraded to accommodate mainline intermodal trains.

[6] Also in 1988, the NYS&W built a connecting track bypassing Maybrook by curving west onto the former Erie Graham Line (current Metro-North Railroad) at a point just north of Sarah Wells Trail in the town of Hamptonburgh.

At Sparta Junction, where the original NYS&W mainline used to cross the L&HR via a wye, a connection has been built to allow more direct movement between the former routes.

The NYS&W also operates a single road train four times a week between Binghamton and Ridgefield Park, New Jersey which traverses the entirety of the remaining L&HR and is the only regular rail traffic between Sparta and Warwick.

Since 2010, the Middletown and New Jersey Railroad leased the Hudson Secondary from NS, and they began operating semi-daily local trains from Campbell Hall to Warwick.

Another section of the line running north from Kennedy Rd in Green Township, New Jersey, has been preserved as the Lehigh and Hudson Rail Trail.

[14] Entering Kittatinny Valley State Park the trail continues along the east coast of Lake Aeroflex 3.5 miles until terminating at Mulford Road in Andover Township, New Jersey.