For work I need to find out when an unrelated firm whose name is the same as ours first used their name, and if they’ve registered it as a trademark. Any clues as to how to gather this info? FWIW, I’m in Washington State, and the other firm is in Washington DC.
Start by calling the Secretary of State for each area. They can give you information, as well as direct you to anyone else you might need to call (for example: in my state, it’s the Sec of State and the Department of Revenue).
Hope that helps!
United States Patent and Trademark Office
There’s a searchable trademark database on that site.