The pattern is very strong: In Seattle you have affluent, largely single people chasing a small supply of urban housing. The result is small household size, an exodus of families to the suburbs, and...
From top: The view east across Lake Washington from Seattle at Interstate 90 (right), with Bellevue in the distance (upper left); Foster Island in the Arboretum; and the view looking up Sammamish...
New demographic figures make clear what a statistical outlier Seattle is, with few families, few kids, high education, and rapid gentrification. Only San Francisco can compare.