Multisite URL Question

I am getting ready to launch a multisite installation of about 282 sites. Each site represents one of our locations.

The problem I am having is the URL. Currently it is something like https://mydomain.com/123 and I want it to be something like https://mydomain.com/locationname but redirect to https://mydomain.com/123

Can someone point me in a direction to accomplish this? I have tried using RewriteRule in the .htaccess file and that didn’t seem to work.

Thanks!