I'm not either in Oregon or Maine, but from my experience with networking - there is no bigger ISP which would have one big IP address pool for whole US.
Usually IP pools are dedicated per area, and size of area is up to ISP. ISP could set IP pool for users from some region depending on their usernames (it's technically possible), but I never heard for such case.
Having that in mind, if you are not OK with IP you get, you can use either proxy or VPN, whatever and whichever suits you better. If you set VPN on your device, then all network apps will see your VPN IP address, if you use proxy - only apps you set to use proxy will have proxy IP address.
So if you need to "cover all your tracks", VPN is better, as no app you are using will have "wrong" IP address.
Edit: Geolocation by IP address using IPv4 MAY be wildly inaccurate. Two simple examples:
ISP does not have enough IP's in it's current IP pool, and it borrows IP range from larger ISP from some other region/country. If you get such IP, until IP pool geolocation data propagates, it will show you are somewhere else, and that somewhere MAY be wildly far, far away. :)
ISP have IP pool DB which is shared by several regions, which are wide apart. In such (rare, but possible) setup only part of IP addresses would be geolocated right, and other would/could have city/state or even continent wrongly attributed. I do not know of such setups for different continents :), but I have found that IP geolocation could easily miss city for 200 or 300 miles. Of course, that depends on your ISP, I speak only from my experience.