1776 - only landowners were allowed to vote
1856 - only white men were allowed to vote
1920 - women were granted the right to vote
1947 - Native Americans given the right to vote
I assume non-Native Americans and non-American born citizens (but were later assimilated) were allowed to vote later on.
So technically Native Americans were the last group to be granted the right to vote, unless you're counting non-natives as well.
