.htaccess rewriterule /state/city/ - html

Question

This will take a bit of explanation so I hope I don't lose everyone here.
I needed to get something like the following:
http://example.com/results.html?state=iowa&city=davenport
turned into:
http://example.com/iowa/davenport/
I was able to accomplish this with the use of these two rewriterules:
RewriteRule ^([A-Za-z0-9-]+)/?$ cities.html?state=$1 RewriteRule
^([A-Za-z0-9-]+)/([A-Za-z0-9-]+)/?$ results.html?state=$1&city=$2
The problem is that in the backend there is "some code somewhere" that is getting broken as a result of the second rewriterule. It has to do with filling in a select box based on the results of another one selected (I don't think that matters though). I think the problem is in that I'm modifying too broadly the /state/city.
Here is a copy of my full (modified for security) .htaccess file:
IndexIgnore *
AddHandler application/x-httpd-php5 .html .htm
RewriteRule ^([A-Za-z0-9-]+)/?$ cities.html?state=$1
RewriteRule ^([A-Za-z0-9-]+)/([A-Za-z0-9-]+)/?$ results.html?state=$1&city=$2
<Files .htaccess>
order allow,deny
deny from all
</Files>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example.com
RewriteRule (.*) http://www.example.com/$1 [R=301,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php [L]
<IfModule mod_suphp.c>
suPHP_ConfigPath /home/USER
<Files php.ini>
order allow,deny
deny from all
</Files>
The code that its screwing up is very complex and its someone else's code. After a couple of hours I've been unable to wade through all of their stuff to even come close to what I may be able to change on their end to get things working.
Does anyone have ANY ideas on what I could do to avoid this problem? I really only have 3 .html files that I'm funneling my frontend code through so I had tried something like a
my rewriterules
and same with using just "files" instead of filesMatch. Everything I've come up with breaks something else or the entire site in one way or another.

Answer 1

First: (i) hostgator won't enable or give you access to rewrite logs; (ii) your suPHP config has syntax errors and hostgator almost certainly does spme of this and the .htacess / php.ini denials in its own root / vhost configs. However, I'll focus on the mod_rewrite elements:
RewriteEngine On
RewriteRule ^([A-Za-z0-9-]+)/?$ cities.html?state=$1
RewriteRule ^([A-Za-z0-9-]+)/([A-Za-z0-9-]+)/?$ results.html?state=$1&city=$2
RewriteCond %{HTTP_HOST} ^example.com
RewriteRule (.*) http://www.example.com/$1 [R=301,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php [L]
I am also assuming that you don't have any .htaccess files in subdirectories with the rewrite engine enabled as these could preempt this under rewrite "Per Directory" precedence rules.
Rules (3) is a simple domain redirector. Rule (4) is a draconian: redirect any URI which is not an existing file or directory to index.php in the current directory, but leaving the query string intact.
Rule (1) and (2) are your new rules. As Mike says, you should include the [L] but since the files cities.html and results.html exist it won't match anyway.
I am curious as to why the trailing slach in the URIs is optional. Better to decide and to fix this.
The issue is that the match criteria for (1) and (2) are two broad and are picking up URIs intended for the general catchall (4). You need to lock this down to make these mutually exclusive. One why is to mine your access logs (which are available with hostgator) to find the standard URIs which the application expects and check that none match (1) or (2) -- However, since most will include a ".", this probably isn't the case. But check.
The other issue is whether the existing scripts use absolute or relative references e.g. <img src="images/myimage.png"> in any output HTML. Here the browser has asked for http://www.example.com/texas/houston say and will therefore look for http://www.example.com/texas/images/myimage.png which doesn't match (1), (2) or (3) and therefore is caught by (4) and passed to /index.php. Ditto CSS files etc. Hence they won't 404 and index.php will get confused and send some default response which will hopelessly confuse the browser.
However, again analysis of the access logs (in this case or USIs with a referrer http://www.example.com/texas/houston) will show you if this is going on.
If your app uses standard subdirectories then you might be able to fix this by a rule (3.1) which looks something like
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond $1/$2 -f
RewriteRule .*?(images|css|styles)/(.+) $1/$2 [L]
though the details will depend on the rest of your application.

Answer 2

I was able to solve it by changing my (relevant) .htaccess entries to the following:
RewriteEngine On
RewriteRule ^([A-Za-z0-9-]+)/?$ cities.html?state=$1
RewriteCond %{REQUEST_URI} !^/signup/
RewriteRule ^([A-Za-z0-9-]+)/([A-Za-z0-9-]+)/?$ results.html?state=$1&city=$2
RewriteCond %{HTTP_HOST} ^example.com
RewriteRule (.*) http://www.example.com/$1 [R=301,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php [L]
The addition being:
RewriteCond %{REQUEST_URI} !^/signup/
HostGator was able to find that the issue was /signup somewhere in a log somewhere, never did find out which log they were able to look at but I assume it was something I didn't have access to.