From Longman Dictionary of Contemporary Englishknock on doorsknock on doorsto go to every house or apartment in an area asking the people who live there for information or support Gathering that information means knocking on doors and asking people questions. → knock
Examples from the Corpus
knock on doors• All I've done since seems to be walk around and knock on doors.• And gathering that information means knocking on doors and asking people questions.• As a young girl I volunteered to knock on doors and enrol pets in the Tailwaggers Club.• I could go up to Albany and knock on doors, and I could almost always get in.• Landlords knocking on doors, demanding money.• She sent Talivaldis to the store for a large loaf of Wonder Bread and knocked on doors, issuing invitations.• Peter: Well, cause trouble, you know; play knocking on doors, throw stones at windows and that. 