The 100 Senate seats are divided into three classes. Only one class is renewed every two years.
Polling stations are open across all the states. Americans are renewing Congress: the entire House of Representatives and one-third of the Senate.
In Austin, the capital of Texas, voters crowd in front of polling stations. Young people there are seeking renewal.
The vote amounts to a referendum for or against the continuation of President Donald Trump's actions.
These midterms are legislative elections. They also offer the opportunity to approve or disapprove of the president's policies.
Lines form to elect representatives and senators.
Everything is particularly at stake in seven states, including Texas.
The vote could result in a clear victory for Democrats over Republicans, according to available information.