The WPUS was formed in 1876, when a congress of socialists from around the United States met in Philadelphia in an attempt to unify their political power. Seven societies sent representatives, and within four days the party was formed under the name of the Workingmen's Party of the United States. The party represented a collection of socialist ideas from different groups, most notably followers of Karl Marx and Ferdinand Lassalle. The influences from these men were felt in the WPUS's trade union policies (which reflected those of the International Workingmen's Association, a Marxist group) and their base as a national organization rather than international (a Lassallean suggestion).
The party at first had little influence over any politics in the United States on a national or local level. Much like the International Workingmen's Association before it, the WPUS was widely viewed as communistic. During the railroad strikes during the summer of 1877, the party showed some of its power, gaining membership in many cities by acting as an organizational and directive force, most notably in Chicago and St. Louis.
Although the WPUS was largely unsuccessful in the strikes it helped lead, on August 6, 1878 the party had managed to gain enough popularity to capture 5 out of 7 spots in Kentucky state legislature. As news spread around the country of the success of the WPUS, more "Workingmen's Parties" formed in cities around the country, some chartered by the WPUS and some not. The end of the Workingmen's Party of the United States came in December of 1878, when it reformed as the Socialist Labor Party.
Philip Foner, The Great Labor Uprising of 1877, (New York: Monad Press, 1977).
Robert V. Bruce, 1877: Year of Violence, (Indianapolis/New York: The Bobbs Merrill Company, 1959).