Baldwin Locomotive Works of Philadelphia, Pennsylvania was the most successful builder of locomotives in the world. Sales of Baldwin steam locomotives in the United States and in foreign markets indicate the economic success of the company and the quality of the product.

The company was founded by Matthias W. Baldwin, a jeweler who opened a machine shop. After he built a steam engine for his shop sometime before 1830, Baldwin was commissioned by a Philadelphia museum to build a miniature locomotive to demonstrate the new steam locomotive technology first developed in England. The success of the model in 1831 brought Baldwin his first order for a full-sized locomotive from the Philadelphia, Germantown and Norristown Railroad Company which was completed in 1832. From this modest start, the Baldwin Locomotive Works grew into a steadily increasing business. In his publication on American locomotive builders, John White wrote that "Baldwin survived because of conservative business methods, sound engineering, and basic good management."

Baldwin was the sole proprietor until 1839 when he took on some partners. Thereafter, the name of the company showed several variations. The following are the firm names under which locomotives have been built: 1831 Matthias W. Baldwin 1839 Baldwin, Vail & Hufty 1841 Baldwin & Vail 1842 Baldwin & Whitney 1846 M. W. Baldwin 1854 M. W. Baldwin & Company 1867 M. Baird & Company 1873 Burnham, Parry, Williams & Company 1891 Burnham, Williams & Company 1909 Baldwin Locomotive Works 1911 The Baldwin Locomotive Works 1951 Baldwin-Lima-Hamilton Corporation

A general decline in business set in during the Great Depression in the 1930s which resulted in various mergers and attempts to revive the business. Although production increased briefly during the second world war, the decline resumed until Baldwin built their last of approximately 70,500 locomotives in 1956.