The Nextdoor platform is indeed nationwide, but you need somebody to set up your local site in your neighborhood, village or town. You need to get people invited to join. It only becomes useful once you reach a critical mass of users in a local area.
The Nextdoor we have here in our California neighborhood is excellent — lots of engaged neighbors.
The Nextdoor we have in our Idaho neighborhood is new and not lots of users yet.
Yes...we’re members of Nextdoor, as is our family.