 The next transport of sheep to North America was not until 1607 , with the voyage of the Susan Constant to Virginia . However , the sheep that arrived in that year were all slaughtered because of a famine , and a permanent flock was not to reach the colony until two years later in 1609 . In two decades ' time , the colonists had expanded their flock to a total of 400 head . By the 1640s there were about 100 @,@ 000 head of sheep in the 13 colonies , and in 1662 , a woolen mill was built in Watertown , Massachusetts . Especially during the periods of political unrest and civil war in Britain spanning the 1640s and 1650s which disrupted maritime trade , the colonists found it pressing to produce wool for clothing . Many islands off the coast were cleared of predators and set aside for sheep : Nantucket , Long Island , Martha 's Vineyard and small islands in Boston Harbor were notable examples . There remain some rare breeds of American sheep — such as the Hog Island sheep — that were the result of island flocks . Placing semi @-@ feral sheep and goats on islands was common practice in colonization during this period . Early on , the British government banned further export of sheep to the Americas , or wool from it , in an attempt to stifle any threat to the wool trade in the British Isles . One of many restrictive trade measures that precipitated the American Revolution , the sheep industry in the Northeast grew despite the bans . 
