A special state election will be held Dec. 10 for a U.S. representative in Massachusetts’ 5th Congressional District, filling the vacancy caused by Ed Markey resigning to became a U.S. senator. The candidates are Democrat Katherine Clark and Republican Frank Addivinola.

For residents not already registered, the deadline for registering to vote is 8 p.m. Nov. 20. Registration can be done  at the Cambridge Election Commission offices at 51 Inman St.

Absentee ballots are also available. Voters who can’t go to the polls on Election Day due to physical disability, religious belief or absence from the city may request an absentee ballot. The deadline to apply is noon Dec. 9. Absentee ballots may be mailed to voters, or absentee voters may choose to vote at the commission’s offices during regular city office hours: Mondays from 8:30 a.m. to 8 p.m.; Tuesdays through Thursdays from 8:30 a.m. to 5 p.m.; and Fridays from 8:30 a.m. to noon. The office will also be open for absentee voting Dec. 6 from 8:30 a.m. to 5 p.m.

For information, visit the commission’s offices or website or call (617) 349-4361.

Polls will be open Election Day from 7 a.m. to 8 p.m.