When I identify which line the links point to, Thomas Leavitt refers to the one born 1616 who immigrated to the Hampton NH area in the 1630s, and his many descendants.
John Leavitt was born 1608 and settled in Hingham MA in the 1630s, after first arriving in Dorchester. Since John Leavitt's descendants are more numerous, we break those branches down to his 5 sons who had families, Samuel, Israel, Moses, Josiah, and Nehemiah, and his daughters.
NEW HAMPSHIRE - Various towns
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Monument in Lancaster, Coos, NH Summer Street Cemetery, with no additional names. Some small stones in the lot are probably Leavitts, but are too deteriorated to read in 2007. Enter cemetery and bear right, near the entrance. Probably Thomas line.