The earliest surviving American portrait print, and the first print of any significance made in New England in any medium, is a woodcut portrait of Boston puritan clergyman Richard Mather probably by the earliest American engraver and first printer in Boston, John Foster.
Five copies of the print survived: American Antiquarian Society, Harvard, Massachusetts Historical Society, Princeton, and University of Virginia. It has been suggested that the print may have originally accompanied copies of a pamphlet entitled The Life and Death of that Reverend Man of God, Mr. Richard Mather, published in Cambridge in 1670, a year after Mather’s death.
"Apparently the cut was made on the flat side of a board. All known impressions are printed from two blocks, the head and shoulders on one block and the balance of the portrait on the other. This use of two blocks is difficult to explain. Foster may have done so deliberately for some unknown reason, or perhaps the block split in the course of its cutting or printing, or possibly Foster, dissatisfied with his cutting of some portion of the portrait, sawed the block in two and recut the portion he did not like on a second block" (Hamilton, Early American Book Illustrators and Wood Engravers 1670-1870, Vol. I (1968) No. 1).
Of the five surviving copies the Harvard impression differs from the others:
"It is on different paper. At least three of the others, and probably all four, are on paper with an eighteenth-century Pro Patria paper mark. One has not been examined. The blocks of the Harvard print match, making the line of the shoulders continuous and natural; in the others there is a distinct step as in the one at the Massachusetts Historical Society. It lacks the others' scratched lines of the sleeves and jacket-opening. It appears to have been printed on a press; the other four show evidence of being 'spooned' proofs. The four have printed titles, though the type is differently positioned in each case. In sum, there is something here which needs explanation.
"The step in the line of the shoulders apparently results from printing with damp blocks, although why they were damp is still an unsolved problem. Wood, of course, expands very much when wet and much much across the grain than with it. Here we have horizontal grain in the upper block and vertical grain in the lower" (Holman, "Seventeenth-Century American Prints," Prints in and of America to 1850, Morse (ed)  25-30).
Shadwell, American Printmaking. The First 150 Years (1969) No. 1., plate 1.