Westmoreland Coal Company is incorporated under Pennsylvania's General Mining Law by John Covode, William Larimer, Herman Haupt, John Scott, and James Magee. All were directly connected with the Pennsylvania Railroad and part of the Philadelphia merchant, banking, and business communities. The formation of the Company was one of the many outgrowths of the completion of the Pennsylvania Railroad, which opened the first all-rail link between Philadelphia and Pittsburgh in 1852.

General Larimer: A Westmoreland County businessman and Treasurer of the Ohio and Pennsylvania Railroads. He moves to Colorado and builds the first house in what later becomes Denver, Colorado.

John Covode: Elected to Congress in 1854, he becomes the first President of the Company.

James Magee: A Philadelphia merchant who succeeded John Covode in 1856, he is one of the organizers of the Pennsylvania Railroad.

Herman Haupt: Westmoreland's first Secretary and Superintendent of the Pennsylvania Railroad. He later becomes head of the U.S. Military Railroad during the Civil War.

William Jackson Palmer: Hired in 1856 to conduct coal-burning experiments. He then becomes Company Secretary. After the Civil War, he moves to Colorado, founds the city of Colorado Springs, and builds the Denver & Rio Grande Railroad.

The Company is formally organized to mine coal in the Irwin Basin of Westmoreland County, Pennsylvania. The business of the Company centers on the gas coal market. The Larimer #1 mine opens shipping 56,223 tons and earning 8% on its initial investment.

Westmoreland contributes indirectly to the growth of the American gaslight industry by furnishing coal to 22 gas companies. By 1861, it is supplying 69 gasworks from Maine to Georgia. Production swells from 90,000 tons to 280,000 tons in 1869. The Pennsylvania Railroad to Philadelphia and Baltimore ships all of the Company's coal.

Coal shipments are delayed/stopped as Pennsylvania Railroad locomotives and rail cars are repositioned north to prevent their capture. General Lee's Army of Northern Virginia marches towards the north to engage the Union Army in Pennsylvania. Both armies meet in Gettysburg on July 1. Coal shipments resume after bridges are rebuilt.

The Company begins experimenting with mechanical mining techniques like the use of the "Green & Boyd Cutting Machine," the "Harrison Pick Machine," and the "Jeffrey Cutting Machine."

 1870:

Westmoreland establishes a relief fund (the precursor to Workman's Compensation) where the Company and employees each contribute 25 cents per month to the fund.

 1871:

Westmoreland Coal is shipped to New York City and enters into long-term contracts with Carnegie Brothers & Company to supply their steel mills in the Pittsburgh area.

 1875:

Westmoreland and neighboring Penn Gas Coal Company enjoy a near monopoly of the gas coal market. The two are the largest bituminous coal companies in the state.

 1880s:

Development of natural gas fields around Pittsburgh and competition from steam coal and coking coal regions start to depress the gas coal markets.

 1883:

The Irwin Basin is successfully organized by the Amalgamated Association of Miners, which later becomes the United Mine Workers of America in 1890.

 1885:

Steam locomotives, used for hauling coal with underground wire ropes (versus the previous method of using mules), were introduced at the Larimer Mine. The Company begins shipments to the West Indies, South America, and the Mediterranean.

 1900:

Westmoreland begins negotiations to buy controlling interest in Penn Gas Coal Company. The transaction is completed in 1905. The purchase is financed by an issue of $2 million in stock and $1 million in 4.25% notes. Penn Gas owned one-third interest in Manor Gas Coal Company.

 1910:

 Westmoreland begins land purchases in West Virginia.

 1913:

The Company's peak production of 4.8 million tons rapidly depletes the Irwin Basin and electricity, natural gas, and petroleum products destroy the gaslight market.

 1916:

Dr. Wentz is the single largest shareholder in the Company and becomes a Director in 1917. 

 1917:

Westmoreland acquires the remaining Penn Gas shares, thus paving the way for a merger of all three firms - Westmoreland, Penn Gas, and Manor Gas - effective January 1, 1918. The consolidated company now owns 14,738 acres stretching the length of the Irwin Basin. S.P. Hutchinson becomes a Director of the Stonega Coke and Coal Company, led by Dr. Wentz.

 1929:

Company President, S.P. Hutchinson, dies unexpectedly. The remaining Directors turn over the Company's management to the Stonega Coke and Coal Company's management headed by E.B. Leisenring, Sr., Chairman of the Board. The Company's offices are moved from its 224 South 3rd Street location to the Fidelity Building in Philadelphia. New management keeps the Company solvent through the Depression and World War II.

 1957:

The Hutchinson leasehold is sold, ending a century of operations in Westmoreland County, Pennsylvania.

 1964:

The old Westmoreland Coal Company is merged into the Stonega Coke and Coal Company, but is re-titled the Westmoreland Coal Company to retain the name that was then the oldest in the industry. Virginia Coal and Iron Company absorbs Westmoreland Inc., which later becomes Penn Virginia Corporation, a land, mineral rights, and investment company.

 1968:

The Company purchases more West Virginia mines from Sprague & Sons and Imperial Smokeless Coal Company, effectively doubling the size of the Company, making Westmoreland the largest "coal-only" firm in the industry.

 1970:

Westmoreland Resources, Inc. is formed to mine coal in Montana on the Crow Tribe land in Big Horn County, Montana.

 1972:

Westmoreland and Penn Virginia Corporation decide to effect a more complete separation of the two firms.

 1976:

Colorado Westmoreland, Inc., is incorporated to mine steam coal in the Grand Mesa coalfields near Paonia, Colorado to begin development of its Orchard Valley Mine.