Clean-up Location data?

Hello-

I'm working on a project where I am filtering images based on geolocation data in my images. I'm noticing LR's metadata panels show inconsistent information the farther back I go. I think part of this might be from the location metadata that is associated to a GPS coordinate differing over time (eg, older pics takin in the US have their Country as "United States of America" while newer ones as "United States"). 

I'd love to normalize the data, and have all the US images consistently show the related metadata (location, sublocation, state, region/country). I know I can do this by temporarily deleting the GPS coordinates then renetering them to trigger a lookup. But this won't scale to my large DB (50K+ images). Is there a way I can do this (update location metadata) in a batch or programatic manner?

Thanks for any insight!