The Pioneer Valley is the colloquial name for the U.S. Commonwealth of Massachusetts's portion of the Connecticut River Valley. The Pioneer Valley region is within three counties in Massachusetts that collectively feature much of New England's most fertile farmland. The lower "Pioneer Valley" is approximately coterminous with Metropolitan Springfield, as Springfield, Massachusetts, is the region's urban center, and the seat of Hampden County. The upper Pioneer Valley region is centered around the small cities of Northampton and Greenfield which are the county seats of Hampshire and Franklin counties.