I'm just finishing a piece on the English origins of Elizabeth (Dowse) Allen, the wife of Samuel Allen. This woman was born in London; married there; came to the colonies with her husband, the Royal Governor of New Hampshire, who died at Newcastle, N.H., and then sort of slips away from the records. Until today. Samuel Allen's estate is administered from his wife's last residence which was Charlestown, Mass. Although in Suffolk County today, in 1708, it was part of Middlesex County, so in volume 12 of the Middlesex Co., Mass. Probate you find Samuel Allen's administration which notes that his wife died by 30 September 1708.
And such is genealogy. A family largely associated with New Hampshire or Boston has important records in a neighboring county where you would not intuitively look.