Isaac was born at Little Compton, Newport, Rhode Island, on 1 August 1839. He was the son of
Charles Wilbur Howland and
Mehitable Hicks. Isaac Wilbur Howland married
Mary Elizabeth Borden, daughter of
Christopher Borden, on 7 December 1863 at Little Compton, Newport, Rhode Island. Isaac Wilbur Howland married
Lucia Ann Seabury, daughter of
Benjamin Seabury and
Elizabeth Tompkins, on 6 December 1893 at Little Compton, Newport, Rhode Island. Isaac Wilbur Howland married
Mary Catherine Seabury, daughter of
John Seabury and
Maria Shaw, after 1901. Isaac Wilbur Howland died on 23 November 1927 at Little Compton, Newport, Rhode Island, at age 88. He was buried after 23 November 1927 at Seaconnett Cemetery, Little Compton, Newport, Rhode Island.