Proper noun
United Colonies
(historical) The Thirteen Colonies that became the United States of America.
In 1641, Massachusetts Bay had passed the first laws to make slavery legal in the English colonies, and these laws had spread to Plymouth and Connecticut with the creation of the United Colonies in 1643. Source: Internet
His elder brother James Cudworth (1612-1682) became an Assistant Governor of Massachusetts and a Commissioner of the United Colonies, Samuel Deane, 'Gen. Source: Internet