Once an important part of the North America transportation net, the number of electric rail lines still in day-to-day revenue service, outside of the Northeast Corridor (and tourist pikes), are but a tiny fraction of the past. They are no longer a key component of the nation's social and economic fabric, nor do they any longer hold the promise of rail transportation's future.

The first electric-powered locomotives appeared in the early 1890s; they represented a challenge to steam because of their lower cost to build, operate and maintain. Those collective advantages however were offset somewhat by the capital cost associated with constructing support infra-structure, generating stations and miles upon miles of overhead wire.

General Electric and Baldwin Locomotive Works were the largest of the builders. GE had been spear-heading electric-powered transportation since 1892. An early achievement was the electrification (equipment installation and locomotives) for the world's first electrified railroad main line; a 3-mile section of the B&O in Baltimore, MD. Both major builders relied on sub-contractors for help: GE used Schenectady, NY-neighbor Alco for the supply of car-body and mechanical components, while Baldwin Locomotive usually teamed with Westinghouse for major electrical components and control systems. On some rare occasions, the roles would be reversed.

Two factors spurred the growth of electric rail lines. The first was a technological break-through in 1896 which saw the development of high-voltage alternating current distribution systems and substations that facilitated the conversion of power into low-voltage direct current (similar to that employed by street cars and interurban). The other was the Kaufman Act of 1923. The New York state law dictated only electric-powered locomotives be used within the boundaries of New York City; comparable laws were passed in other cities and states . The New York declaration was meant to improve transportation safety; smoke-filled tunnels caused by steam engines had become hazardous to public transportation. (Note: the new law was also arguably a fore-runner of the "green" and "sustainable design" practices that took hold a half century later.

Initially, freight units were primarily straight electric, but before long supplemental battery or diesel generator capability were made available. And, in a some instances heavy-duty freight locomotives were built utilizing all three modes (tri-power). Steeple center-cabs tended to be straight electric because of space limitations. These subject will be explored periodically in the months ahead. For purposes of future discussions (and convenience) only, electric freight motors are divided into different types based on car-body configuration, irrespective of horsepower and weight, pantograph or trolley pole: