htaccess - creating directories and files of the same name - .htaccess

Question

I want to create a bunch of files without an extension showing at the end. The easiest way to do that was to do this:
/usa/index.php
/usa/alaska/index.php
/usa/alabama/index.php
/usa/california/index.php
What I want to do is this
/usa/alaska.php
/usa/alabama.php
/usa/california.php
and have it show up as:
/usa/alaska
/usa/alabama
/usa/california
However, I have one more level I want to add to this, the cities
/usa/alaska/adak.php
/usa/alaska/anchorage.php
/usa/california/los-angles.php
I don't want the ".php" showing up, but then each state exists as both a file and a directory. What I want is an htaccess rule that serves up the file version of the file, not the directory which is the default. I also want to strip the .php off of the end of the files so the final result looks like
/usa
/usa/alaska (alaska.php)
/usa/alaska/adak (adak.php)
I know I can get close to this by creating all the directories and using index.php for each directory, but then I will have thousands of directories each with one file in it and updating is a pain in the butt. I would much rather have one directory with 1000 files in it, than 1000 directories with 1 file in it.
Please, can someone point me in the right direction and know that I am doing this for all 50 states.
Jim

Answer 1

I would also suggest using a single php (e.g. index.php) file and redirecting all urls starting with usa to it, instead of separating them in different directories and files. The you'd need a couple of rewrite rules like the following
RewriteEngine On
RewriteRule ^usa/([^/.]+)$ index.php?state=$1 [L]
RewriteRule ^usa/([^/]+)/([^/.]+)$ index.php?state=$1&city=$2 [L]
So then in your index.php you'd only need to check the $_GET parameters.
Update:
If you don't feel comfortable enough to use a database and pull the needed data from there you could always use the parameters to dynamically include/require the needed files. Something like this
<?php
$source = ''; //or the 'ROOT' directory
if(isset($_GET['state'])) $source .= $_GET['state'].'/';
if(isset($_GET['city'])) $source .= $_GET['city'].'.php';
include($source); // here $source would be something like 'alaska/adak.php'
// and is assumed that the dir 'alaska' is on the same
// level as 'index.php'
?>
But to answer your original question nevertheless you could use the following .htaccess
RewriteEngine On
RewriteRule ^usa/([^/.]+)$ usa/$1.php [L]
RewriteRule ^usa/([^/]+)/([^/.]+)$ usa/$1/$2.php [L]

Answer 2

what about creating just one single file:
/usa/index.php
With
$_SERVER["REQUEST_URI"]
you can read the current URI.
Well, now if a user enters "http://domain.foo/usa/alaska" for example, he will get an 404 error of course.
But to call your index.php instead, you could write this line to the .htaccess:
ErrorDocument 404 /usa/index.php
Now the index.php receives everything what is written to the URI and you can match the result and include files or handle errors.
But maybe there is a better solution with .htaccess only, don't know. :)