District Of Columbia
The District of Columbia is the only non-state to be enfranchised for presidential elections, gaining electoral votes through the ratification of the 23rd Amendment in 1961. That amendment gave residents of the nation's capital a share of electors proportional to its population (like the states), but limited it to no more electors than the least populous state. This meant three electoral votes in 1964, and that number has not changed. The vote here has always been heavily Democratic; no Republican has ever won an electoral vote. In the 2016 election, Hillary Clinton received about 22 votes for each one vote for Donald Trump.