If we are spitballing, I think there should be an actual file associated with the text so you can see the vote. A file makes it trivial to grep for "Senator X".
Not git, but Congress actually does have quite a bit of data digitized. A random example[0] -they even provide XML. The Congress data is going to give you all bills - many of which do not pass, so a different mission than this project.
But getting the entire country's law into git is already an impressive feat.