Phineas Brigham, Sr. was born 7 October 1757 in Marlborough, Middlesex County, Massachusetts to George Brigham (1730-1808) and Mary Bragg (1735-1822) and died 17 March 1813 Eaton, Madison County, New York of unspecified causes. He married Susanna Howe (1764-1813) 1785 in Marlborough, Middlesex County, Massachusetts.
Children
| Name | Birth | Death | Joined with |
| Phineas Brigham (1784-1847) | 31 December 1787 Southborough, Worcester County, Massachusetts | 17 September 1852 Madison, Madison County, New York | Susan Ames (1791-1852) |
| Timothy Brigham (1786-1829) | |||
| Susanna Brigham (1787-1809) | |||
| Sophia Brigham (1792-) | |||
| Louisa Brigham (1794-1796) | |||
| Louisa Brigham (1797-1857) | |||
| George Howe Brigham (1799-1881) | |||
| Fitch Brigham (1803-1844) | |||
| Salmon Brigham (1805-1890) | |||
Siblings
| Name | Birth | Death | Joined with |
| Phineas Brigham (1754-1755) | |||
| George Brigham (1756-) | |||
| Phineas Brigham (1757-1813) | 7 October 1757 Marlborough, Middlesex County, Massachusetts | 17 March 1813 Eaton, Madison County, New York | Susanna Howe (1764-1813) |
| Timothy Brigham (1759-) | |||
| Louisa Brigham (1760-1771) | |||
| Ashbel Brigham (1762-1771) | |||
| Mary Brigham (1763-1771) | |||
| Thankful Brigham (1765-1824) | 7 May 1765 Marlborough, Middlesex County, Massachusetts | 14 December 1824 Marlborough, Middlesex County, Massachusetts | Daniel Brigham (1760-1818) |
| Zerviah Brigham (1767-1771) | |||
| Samuel Brigham (1769-1771) | |||
| Stephen Brigham (1771-1771) | |||
| Samuel Brigham (1772-) | |||
| Maru Louisa Brigham (1773-1775) | |||
| Stephn Brigham (1774-1775) | |||
| William Brigham (1779-) | |||