For a good part of my work, I traveled to various states and performed "work" in the sense I shot travel photos for magazines. BUT, according to my tax guy, my state tax was only relevant in the state where I lived, and the state where I received my assignments -- Massachusetts at the time. I never filed any state tax in any other state because according to my tax guy, no matter where I traveled to perform my assignments, I got paid only in my home state. So, it's where you get paid, where the home offices is that assigns the work.
It may be different if you go to a state, say, and work on some equipment, or install some equipment. Otherwise, even doing IT support for example, you'd have to pay tax in every state where you 'helped' anyone untangle IT on a web contact. That would make no sense. So it makes more sense that you pay tax in the state where you receive your pay check.
