WASHINGTON — Democrat Ayanna Pressley has completed her quest to become Massachusetts’ first black woman elected to Congress.

Pressley is also the first African-American to serve on the Boston City Council. She sailed through Tuesday’s general election to Congress unopposed, two months after unseating 10-term Rep. Michael Capuano in a primary that was a national political stunner.

With no Republican in the race in the heavily Democratic district, her upset victory in the primary had all but assured Pressley the House seat, with only the remote possibility of a write-in campaign to potentially stop her.