Samuel Wilbur Jr. was an early settler of Portsmouth in the Colony of Rhode Island and Providence Plantations, and one of seven original purchasers of the Pettaquamscutt lands which would later become South Kingstown, Rhode Island. His father, Samuel Wilbore, had been an early settler in Boston who was dismissed from the Massachusetts Bay Colony for supporting the dissident ministers Anne Hutchinson and John Wheelwright, becoming one of the signers of the compact that established the town of Portsmouth. The subject Samuel was willed his father's Rhode Island lands, and appears to have lived in Portsmouth most of his life. He married Hannah Porter, the daughter of another signer of the Portsmouth Compact, John Porter. Beginning in 1656 Wilbur held a number of important positions within the colony, including Commissioner, Deputy to the General Assembly, Assistant to the Governor, and Captain in a Troop of Horse. He wrote his will in August 1678, though it was not probated until more than three decades later. Wilbur was held in high esteem within the colony and was one of a small group of men named in the Royal Charter of 1663, signed by King Charles II of England, and becoming the guiding document of Rhode Island's government for nearly two centuries.

Samuel Wilbore was one of the founding settlers of Portsmouth in the Colony of Rhode Island and Providence Plantations. He emigrated from Essex, England to Boston with his wife and three sons in 1633. He and his wife both joined the Boston church, but a theological controversy began to cause dissension in the church and community in 1636, and Wilbore aligned himself with John Wheelwright and Anne Hutchinson, signing a petition in support of dissident minister Wheelwright. In so doing, he and many others were disarmed and dismissed from the Boston church. In March 1638, he was one of 23 individuals who signed a compact to establish a new government, and this group purchased Aquidneck Island, then known as "Rhode Island", from the Narragansett Indians at the urging of Roger Williams, establishing the settlement of Portsmouth.