The Delaware, Lackawanna & Western Railroad Company was incorporated in Pennsylvania on April 7, 1832, as the Liggett's Gap Railroad Company. Its name was changed to the Lackawanna & Western Railroad Company on April 14, 1851, and to the DL&W (Delaware, Lackawanna & Western) Railroad Company on March 11, 1853, at which time it absorbed the Delaware & Cobbs Gap Railroad Company.

The first section of the railroad, from Scranton to Great Bend, opened in October 1851. The railroad's Southern Division was opened between Scranton and the Delaware River on May 27, 1856, forming a more direct route to New York City in connection with the Warren Railroad and the Central Railroad of New Jersey. The DL&W leased the Morris & Essex Railroad in 1868 and, after upgrading it to permit a heavy coal tonnage, secured its own line to New York Harbor. Other extensions carried the Lackawanna to Utica, Syracuse, Ithaca, and Oswego in central New York State and to Buffalo in the early 1880s. The DL&W had a particular advantage in that it was allowed to operate coal mines directly. The DL&W began mining on its own account in 1851 when a Coal Department was organized. The Lackawanna was exceptionally well placed to supply both New York City and New England via the Southern Division and upstate New York, the Great Lakes, and Canada via the Northern Division.

The DL&W was still bound by its 1856 traffic contract with the Central of New Jersey, and on March 16, 1872, the two companies agreed to consolidate, being managed by a joint committee of directors from the two companies. However, the two companies were now competitors, with parallel lines between Scranton and New York. The consolidation broke up after about a year over arguments as to which company would be the dominant partner. All connections between the two companies were severed in 1875.

During the long presidency of the conservative Samuel Sloan (1867-1899), the road became extremely prosperous as a coal hauler. Financial control was exercised by Moses Taylor and his National City Bank of New York, who had bought into the company at the time of the Panic of 1857. In March 1876, the DL&W converted from a 6-foot gauge to a standard gauge.

In 1880 Jay Gould acquired an interest in the company and promoted its extension to Buffalo (1882), giving it a significant share of the truck line business for the first time. However, Taylor and his successors refused Gould any further voice in the management. In 1890 William Rockefeller became a director, reflecting the alliance between the Standard Oil group and the National City Bank.

William H. Truesdale replaced Sloan as president and began a massive modernization of both the company's management and the physical plant. The company began issuing full annual reports for the first time since 1857. Two major line relocations were built to the highest engineering standards across western New Jersey and between Scranton and Binghamton to improve grades and clearances. They featured massive cuts and fills and huge viaducts, the Tunkhannock Viaduct, 240 feet high, is the largest concrete arch bridge in the world. The DL&W was a pioneer in the adoption of reinforced concrete construction for all types of structures. Under Truesdale's successor, John M. Davis, the principal New Jersey commuter services were electrified in the early 1930s.

After successful government prosecution of the other anthracite railroads for antitrust violations, DL&W voluntarily divested itself of its Coal Dept., which became the Glen Alden Coal Company in 1921.

After World War II, the DL&W hoped to merge with its principal western connection, the Nickle Plate, but was unsuccessful. After continuing losses from commuter service and heavy storm damage to its main lines in 1955, the company explored consolidation with the parallel Erie Railroad. The merger, forming the Erie Lackawanna Railroad Company, took effect on October 17, 1960.