Suppose that Sarah has a job which requires near constant travel on airplanes.
Also suppose that Sarah does not own a house, or rent an apartment.
Sarah lives out of hotels, motels, air-BnBs, etc... for at most a week at a time.
Almost all personal possessions Sarah own fit inside of a suitcase. Sarah owns a laptop computer, a cellphone, various clothing items, etc...
I realize that most people who travel for work do have something like an apartment where they live at least one month out of the year, but that's not what I'm talking about here. Sarah truly has no fixed-home. Suppose that Sarah travels year-round, and is never in the same city for more than one week.
How would Sarah pay taxes to the U.S. government? Specifically, state-level income tax? To which state would Sarah pay taxes?