By 1860, Aiken owned the entire Jehossee Island, and the plantation produced 1.5 million pounds of rice in addition to sweet potatoes and corn.

[3] Unfortunately, William Sr. was killed in a Charleston carriage accident and never saw his namesake town of Aiken, South Carolina.

After two months and 133 ballots, Aiken lost the race to Nathaniel P. Banks by a vote of 103 to 100, in what has been termed "the longest and most contentious Speaker election in House history".

Following the Dred Scott decision, Aiken began traveling to more temperate Northern locations in the summer with some of his slaves, and became an early patron of the University of Minnesota, loaning it some $28,000 (approximately $750,000 in 2016 terms).

Aiken died at Flat Rock, NC, September 6, 1887, and was interred in Magnolia Cemetery at Charleston, South Carolina.