Steam power was first used to supplement the fully developed hydropower sources in Lowell in the 1860s, and by the mid-1870s, it was the dominant energy source. Electricity allowed the mills to run on hydroelectricity, instead of direct-drive hydropower. These improvements allowed Lowell to continue increasing its industrial output with a lesser increase in the number of workers. However, the move away from pure hydropower was leading to Lowell being eclipsed by cities with better locations for the new power sources. For example, in the 50 years after the Civil War, Fall River, Massachusetts and New Bedford, Massachusetts both became larger factory towns than Lowell based on output. The reason was largely because their seaport locations made the importation and exportation of goods and materials, and particularly coal, more economical than the considerably inland, and therefore only accessible by train, Lowell. By 1920, it was being seriously suggested that the Merrimack be dredged from Newburyport to Lowell so that barges could access the city. However, the events of the 1920s ensured that would never happen.