The Experience provides a “search by city”, “search by state”, and “search by country” feature. This search form element, when enabled, will build a drop down list based on the locations in your database. This is meant to provide a hint to the user where your locations are.
The legacy system was a simple “address input” feature. When a user selected an entry from the drop down list it types the text into the address box. When the user clicks the search button it looks for locations closest to that location based on your other search form settings. If your default radius is 100 miles and the user selects the state of Texas, this system will search for all locations within 100 miles of Google’s estimated “center of Texas”.