While the headquarters have been south of downtown Seattle for years.
Boeing is actually a Delaware corporation... tax reasons.  Over the years
Boeing has expanded by merging and buying other companies.  Acquistions
included North American Rockwell (space shuttle),  Hughes (satellites) and
the merger with McDonald Douglas.  While Seattle employees may be
disappointed the employees in St. Louis,  Dallas, Anaheim, Wichita, Coco
Beach, etc are probably cheering and saying it is about time.