Although Newcastle wasn't officially Incorporated until 1994, it still played a major role in the development of Seattle and the Seattle region long before that. It was one of the region's earliest coal mining areas and the railroad passageway from it to Seattle was the very first in King County. The real estate for sale in Newcastle continues to grow and flourish as the trails in the area are continuously being integrated into new housing developments and parks. Back in 2011, CNN Money's rankings of best places to live in the United States had Newcastle listed as number 17.