History of the United States By arenas amaris Oct 27, 2015 1620 They also started early in Plymouth and Massachusetts. Oct 27, 2015 1776 American colonists declared their independence which led to the Revolutionary War. Oct 27, 2015 1783 After several yearsoof fighting, Great Britian recognized American Independence Oct 27, 2015 1787 55 delegates met in Philadelphia to change the Articles. Instead, they decided to write a constitution for an entirely new National Government. Oct 27, 2015 1803 The country doubled in size when president Thomas Jefferson purchased the vast Louisiana Territory from France. Oct 27, 2015 1820 The United States also gained Florida from Spain and part of the Oregon Territory from Britian Oct 27, 2025 1607 The colonists started early settlements in Jamestown, Virginia Thecolonists started early settlments in Jamestown, Virginia.