Google's John Mueller had to warn one SEO that he should not go ahead and build out 1,300 city based landing pages, with the strategy of trying to rank for your keyword phrase + city name. He said that would be a doorway page and against Google's guidelines.
Here are those tweets:
That sounds like doorway pages, not something I'd recommend.
— 🍌 John 🍌 (@JohnMu) December 10, 2019
Now, this is not new. First, Google's help document defines doorway pages as:
Doorways are sites or pages created to rank highly for specific search queries. They are bad for users because they can lead to multiple similar pages in user search results, where each result ends up taking the user to essentially the same destination. They can also lead users to intermediate pages that are not as useful as the final destination.
One example Google gives is "Substantially similar pages that are closer to search results than a clearly defined, browseable hierarchy."
Since 2008, Google has said city/state landing pages are doorway pages and Google reinforced it twice in 2015.
Forum discussion at Twitter.