The Archives search engine is at: http://www.usgwarchives.net/search/search.cgi/
Note the simple search engine will only search for separate terms such as John or Smith in our donated text transcriptions.
To search only Colorado enter /co/ in the "URL matchs" section
of the form.
Google also has a USGenWeb Archives search set up. It is at http://usgwarchives.net/search/