Where does GitHub store data/files?

Main servers are in the US based on my observations. git pull from San Francisco based server is lightning fast while Australian servers are significantly noticeably slower. Possibly some additional regional hubs too.

They were at some point hosted with racksapace, no idea if still are or not. https://www.quora.com/How-many-physical-virtual-servers-does-GitHub-have

Currently Github seems to have its own datacenters in the USA: Northern Virginia and Seattle. https://githubengineering.com/evolution-of-our-data-centers/