• Isaac Allerton was born ca. 1586, (he said he was about fifty-three years old in September 1639). A Leiden Separatist and 1620 Mayflower passenger, Allerton was second in authority only to Bradford in the early years of the colony. However, Bradford felt that Allerton had abused the trust the colonists placed in him, and Allerton left the colony in the 1630s for other parts. A most enterprising man, he engaged in commercial pursuits at Marblehead and in Maine and later resided at New Amsterdam. He cleared his debt to the Adventurers by a contract of 12 May 1646 in which he ratified what William Bradford, Edward Winslow, and Myles Standish, as agents for Sherley, Andrews, and Beauchamp, had done or would do about the sale of his lands, goods, and cattle “provided they do clearly acquit him from all debts and demands.” He died at New Haven in February 1658/59, leaving little estate except debts he claimed were due him.
After the death of his first wife, Mary Norris, he married (2) Fear Brewster, and (3) widow Joanna Swinnerton. Allerton left a number of descendants in New England, and his son Isaac migrated to Virginia, where the line was carried on under the Allerton, Lee, and Travers surnames. [20, p 234]

• He removed to New Amsterdam about 1639, and in 1643 was one of the Eight Men of the New Netherlands. In 1647 he purchased a tract of land, and built a warehouse and residence, where Peck Slip now is. He was also often at New Haven after leaving Plymouth, and became a resident there as early as 1646, although retaining his business and residence at New Amsterdam. He was Deputy Governor 1621 to 1624. Assistant 1624 to 1631, and also in 1633. [793, p 115]

• He may have been with the Pilgrims in Amsterdam about 1610, and earlier as a merchant in Holland, but most likely he joined the Robinson Church with others from London. It is known he was of London before 1609, and that he was admitted as burgess of Leyden, Holland, in 1614. [1868, p 5]

• Isaac Allerton may have come from the vicinity of Ipswich, co. Suffolk, England.  He first appears in Leiden, Holland records on 4 November 1611, when he married Mary Norris.  Isaac had a sister named Sarah who also resided in Leiden, and who married future Mayflower passenger Degory Priest.  He was probably also related, perhaps a brother, to Mayflower passenger John Allerton.
Isaac Allerton is one of the most complex figures in early Plymouth Colony. He was elected assistant to Governor Bradford in 1621, and continued in that capacity well into the 1630s. He was the individual sent to handle most of the buyout negotiations with the London investors that commenced in 1627, and continued through the early 1630s. Allerton soon began to take advantage of his position by engaging in some personal trading deals, and engaging the Pilgrims' joint-stock company in business ventures they had not authorized. After driving the colony deeper into debt with ill-advised business opportunities, he was eventually removed and replaced by Edward Winslow. After the death of his wife Fear in 1634, he retreated to the New Haven Colony and married there to Joanna Swinnerton. [7143, p 1]