"The subject of this sketch descends from James Hamlin or Hamblin, a Puritan who was driven out of England on account of his religious opinions. He settled at Barnstable, Cape Cod, Massachusetts, 1639. Thomas Hamlin, the great grandfather of Mahlon P. Hamlin, emigrated to New Jersey, and made settlement as a tenant of James Alexander, in what is now Hunterdon County, on the Bloomsbury Mountain about midway between Bloomsbury and Little York. Subsequently he made settlement in Greenwich township, now Warren County."
A little lesson in going sideways. I would not have found this if I hadn't bothered with Thomas, brother of John sr., and pursued the Bloomsbury Mountain reference embedded in the reference to Hunterdon. And it's only by paying attention to what happened where (Time and Place matter A Lot) that I knew to disentangle Huntington and Hunterdon and treat them as separate locations for separate generations in the Hamlin history.