Elisha K. Root was born in 1808 near Springfield, Massachusetts, and became one of New England's most accomplished machinists. He began his industrial apprenticeship at the age of ten working as a bobbin boy in the textile industry. At fifteen Root served as an apprentice at a machine shop in Ware, also in Massachusetts. He then honed his industrial skills in a machine shop in Chicopee, Massachusetts.

Root made the acquaintance of Samuel Colt, who, in 1829 at the age of 15, detonated one of his inventions--an electrically-ignited submarine mine--which doused the crowd with muddy water. Root was among the onlookers, and, as the story goes, it was Root who helped Samuel Colt escape the crowd's wrath.

In 1849, when Colt was looking for a superintendent to run his munitions factory, he naturally turned to Root, who was by then known as the best mechanic in the Connecticut valley. At the time, Root was working for the Collins Company, which made axes, and Root was busy building machines (along with his reputation) to produce the axeheads more efficiently. Colt lured Root from the Collins factory by doubling his previous salary, an action that reportedly made Root the highest paid "mechanic" in New England.

Root immediately set about transforming the Colt firearms factory, building nearly 400 machines to produce the interchangeable parts that made the Colt factory the model of industrial efficiency. It was Root's mechanical genius that is credited with making the Colt firearms company a success. Among Root's most successful machine tools was the "universal" miller. His miller could be easily adapted to perform a great variety of metal-cutting operations, each of which previously required a separate machine. The machine was made for the Colt factory at the Lincoln iron works in Hartford, Connecticut, and became known as the "Lincoln Miller." With more than 150,000 sold, it became the most commonly used machine tool in America.

Elisha Root continued to apply his successful machine tool inventiveness to all aspects of the Colt manufacturing process. When Samuel Colt died in 1862, Root took over as president of the Colt armories. He ably managed this now very large and prosperous business until his death three years later.