Stephen Palfrey Webb was born on March 20, 1804, in Salem, Massachusetts, to Stephen and Sara Webb. He graduated from Harvard University in 1824, and he was admitted to the bar two years later. He married Hannah Robinson on May 26, 1834, and their daughter Caroline was born around 1846.
He supported the Whig Party, and he served in the state legislature in the 1830s. He then served as mayor of Salem from 1842 until 1845. He moved to San Francisco, California, around 1853. He joined the Know Nothing Party in the 1850s, and he served as mayor of San Francisco from 1854 until 1855. He eventually returned to Salem and joined the Republican Party. By 1860, he owned $9,000 of personal property.
He became mayor of Salem again in 1860, and he remained in office until 1862. He then served as city clerk from 1863 until 1871. He died of “old age” in Brookline, Massachusetts, on September 29, 1879.