The American Locomotive Company (ALCO) was a prominent manufacturer of locomotives in the United States, established in 1901. It played a significant role in the development of steam, diesel, and electric locomotives, becoming one of the largest locomotive builders in the country. ALCO's products were widely used by various railroads, contributing to the expansion of the American railway system. Throughout its history, ALCO produced thousands of locomotives, including the famous ALCO PA and ALCO S-2 models. The company faced challenges in the mid-20th century due to competition from other manufacturers and changing technologies, ultimately ceasing production in 1969.