That IP address you shared is a CloudFlare IP address: https://bgp.tools/prefix/173.245.58.0/24#asinfo

I would have said that perhaps you are getting requests from people using their WARP proxy product - which isn't that wild. The reverse DNS on that page though suggests that the range is mainly full of name-servers, which would be strange to get requests from but I have no idea what cloudflare does on its network.

As for the multiple datacentre thing - one IP address can be Anycast-ed to multiple actual hosts in different physical locations.

For example, if I ping 173.245.58.0, I get a response in 11ms from my location here in Helsinki. At the speed of light this means travelling 3,300KM (0.011s * 3x10^8m/s) which doesn't get me anywhere near the States. So again, nothing exciting about 1 IP address coming from different locations. If you look at your raw logs - you might see some headers from cloudflare with more clues.

It's interesting, but as others have mentioned, not worth worrying about.