D.C. Mun. Regs. tit. 3, § 703
703.1 Polling places in which elections are to be held shall be opened at 7:00 a.m. on the date required by law for the election and shall remain open for voting until 8:00 p.m., except in instances when the time established for closing the polls is extended pursuant to a federal or District of Columbia court order or Board order.
703.2 All persons standing in line at a polling place at the close of polls shall be permitted to vote, if otherwise qualified.
703.3 At the close of polls, a polling place official shall take a position at the end of any existing line of prospective voters, and only persons standing in front of the official at that time shall be permitted to vote.
703.4 By order, the Board may, at its discretion, extend polling hours at a precinct in order to resolve unforeseen emergency situations on Election Day.
SOURCE: Final Rulemaking published at 39 DCR 2467, 2480 (April 10, 1992); as amended by Final Rulemaking published at 50 DCR 11074-11075 (December 26, 2003), incorporating by reference the text of Proposed Rulemaking published at 51 DCR 5041 (May 14, 2004); as amended by Final Rulemaking published at 51 DCR 7403 (July 30, 2004); as amended by Final Rulemaking published at 57 DCR 4245, 4247 (May 14, 2010); as amended by Emergency and Proposed Rulemaking published at 57 DCR 7081 (August 6, 2010)[EXPIRED]; as amended by Final Rulemaking published at 57 DCR 11123 (November 26, 2010); as amended by Final Rulemaking published at 62 DCR 14744 (November 13, 2015); as amended by Final Rulemaking published at 65 DCR 6543 (June 15, 2018).