I read that candidates for Congress can knock on doors as a way to campaign. Is this a common practice or something that is rare? I read that AOC knocked on many doors, but I would think this would be specific to places with a high population density like New York City. I am curious if candidates to the House of Representatives do it before an election for only a few hours as an opportunity to take photographs or if they do it for hundreds of hours to reach large numbers of people.
It is obviously impractical to go door to door in farm country. The houses are too far apart. That said, even in rural areas, there are more concentrated areas, towns or even just housing plans, where someone can go door to door reasonably.
For example, Tim Holden represented a relatively rural district. But he went door to door in areas that were more heavily populated in his 2002 bid for reelection against another incumbent (they were redistricted into the same district). I'm not sure that these were mainly photograph opportunities, but he did use them to issue press releases.
Rick Santorum was also known for knocking on doors.
Another issue with Alexandria Ocasio-Cortez's election was that it was a primary election. Primaries tend to have lower turnout. So it can be particularly important to go door to door to get people to go to the polls at all. She won with less than seventeen thousand votes. She would go on to get more than a hundred thousand in the general election. And that's still low compared to some congressional districts, closer to the lowest turnout than the highest.
Here are instructions for leveraging door to door. Note how the candidate is only part of it. An important part certainly, but just part. There is also delivering literature and connecting with voters who don't answer the door by mail. It doesn't mention it, but there are also secondary effects. Having the candidate visit gives neighbors a reason to talk. That discussion can also lead to more people supporting a candidate.
It's also worth noting that other people in the campaign can knock on doors. For example, people associated with Barack Obama visited my parents in 2008. The candidate is most effective, but others can be effective too.