Final answer:
Washington State's population center is influenced by its geography and the shipping industry. The Pacific Northwest's natural resources and waterways have traditionally supported indigenous cultures, and now underpin a significant urban population and economic growth.
Step-by-step explanation:
The population center of Washington State has shifted due to the natural geography and the development of the shipping industry along its coastline. In the Pacific Northwest, waterways and the bounty of the sea have historically shaped the livelihoods and cultures of the indigenous people.
Today, this region is known for its bustling urban centers and is a hub for major corporations. The geography of the coast, with its numerous inlets and harbors, is particularly conducive to shipping and trade, contributing significantly to the area's economic growth and making it the population center of the state.