Key moments from a night of midterm election firsts

Americans are electing members of Congress, which is made up of the House of Representatives and the Senate. All 435 House seats are up for election. In the Senate, only 35 of 100 seats are being contested because senators serve six-year terms.

This results tracker shows both the races being decided now and the 65 seats that are not up for election this year - 34 held by Democrats and 31 by Republicans. Democrats have won both the US Senate and House of Representatives, taking control of Congress for the rest of Donald Trump's presidency. Even before the full vote tallies are known, projected results have provided the party with a number of things to celebrate - and rival Republicans some reasons to commiserate.

Democrats have tallied up victories in states that were comfortably won by Trump two years ago, registering sizeable swings in the likes of Texas, Kansas, Ohio and South Carolina.