After John Winthrop set up his government in 1630 on Massachusetts Bay the history of the Plymouth colony ceased to be of first importance, and therefore the remaining events in her annals need not take much space.

In 1633 the people of Plymouth established a fort on Connecticut River above the Dutch post, so as to intercept the Indian trade, and in 1639 they renewed the ancient league with Massasoit.[23] In 1640 they had a dispute with Massachusetts over the boundary-line, which was arranged by a compromise, and in 1641 William Bradford deeded to the freemen of the corporation of New Plymouth the patent of 1630, granted by the Council for New England to him as trustee for the colony.[24] Finally, in 1643, Plymouth became a member of the New England confederation.
A survey of these twenty-three years (1620-1643) shows that during the first eleven years the increase in population was very slow.

In 1624 there were one hundred and eighty settlers and in 1630 but three hundred.

The emigration to Massachusetts, beginning in 1629, brought about a great change.

It overflowed into Plymouth, and in twelve years more the population had increased to three thousand.[25] The new settlers were a miscellaneous set, composed for the most part of "unruly servants" and dissipated young men, whose ill conduct caused the old rulers like Bradford to question "whether after twenty years' time the greater part be not grown worser."[26] Nevertheless, the people increased their "outward estate," and as they scattered in search of fertile land, Plymouth, "in which they lived compactly till now, was left very thin and in a short time almost desolate." In 1632 a separate church and town of the name of Duxbury was formed north of Plymouth; and eleven years later the towns of the Plymouth colony were ten in number: Plymouth, Duxbury, Scituate, Taunton, Sandwich, Yarmouth, Barnstable, Marshfield, Seeconck, or Rehoboth, and Nausett.[27] At the first arrival the executive and judicial powers were exercised by John Carver, without any authorized adviser.