Search form Java Script

I was hoping someone could help me in a project that I’m working on. I’m searching for some ideas on how to populate a drop downs on a search form. I am using Word Press platform that runs on PHP MySQL as the back end database. For instance, the form will have U.S States followed by Counties then cities;

and if for example you select Pennsylvania it will automatically select Pennsylvania counties on the next cell. Ones you select a county then it will do the same thing to the cities and so fourth. Ones you click on the city and hit “Submit or search” It will find the page within your website that you selected for that purpose. An example would be find “Philadelphia” page IF you select Philadelphia and hit search.

I’m thinking JavaScript or JQuery?

Thank you guys for all your help!

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