There's a tech boom going on in the Seattle area (Microsoft, Amazon, Google, Adobe, Boeing, etc.), which has no income tax.
Boeing though just built a new facility in another state because of union issues (apparently).
Bottom line is that it's a part of the business decision, but not the only part and maybe not even the biggest part.
This is especially ironic (and painful) for Kansas since Boeing had been a major employer in the Wichita area for decades. It sold its Wichita Commercial Airplanes division to Spirit AeroSystems in the mid-2000s.