<P> At first only the imperial powers of Europe had the resources to support and expand settlements in North America . As time went on the colonies became more powerful and sought independence from the Old World . These demands for more autonomy sparked several wars, including the American Revolutionary War (1775--1783) and the Mexican War of Independence (1810--1821). The last major colonial power on the continent, the United Kingdom, granted dominion status to Canada in 1867 and slowly turned over its remaining land to that country over the next 100 years, with the last land transfer being the Dominion of Newfoundland in 1949 . Throughout this period, France maintained the small North American territory of Saint Pierre and Miquelon off the coast of the island of Newfoundland . </P> <P> From independence, the United States expanded rapidly to the west, acquiring the massive Louisiana territory in 1803 and fighting a war with Mexico to push west to the Pacific . At the same time, British settlement in Canada increased . US expansion was complicated by the division between "free" and "slave" states, which led to the Missouri Compromise of 1820 . Likewise, Canada faced tensions between settlers, including French and English communities, and the colonial administration that led to the outbreak of civil strife in 1837 . Mexico faced constant political tensions between liberals and conservatives, as well as the rebellion of the English - speaking region of Texas, which declared itself the Republic of Texas in 1836 . In 1845 Texas joined the United States and in 1867 the United States acquired Alaska from Russia . The last major territorial change occurred when Newfoundland joined Canada in 1949, but there have been a number of small adjustments like the Boundary Treaty of 1970 where the city of Rio Rico, Texas, was ceded to Mexico . </P>

Who claimed almost all the land west of the mississippi river