Jones Island is an industrialized peninsula in Milwaukee, Wisconsin. It began as a marsh island between the Milwaukee and Kinnickinnic rivers, and now forms the city's inner harbor design. Extensive filling and channelization of the area began in the mid-19th century when city co-founder Byron Kilbourn advocated a "straight cut" from the Milwauke…Jones Island is an industrialized peninsula in Milwaukee, Wisconsin. It began as a marsh island between the Milwaukee and Kinnickinnic rivers, and now forms the city's inner harbor design. Extensive filling and channelization of the area began in the mid-19th century when city co-founder Byron Kilbourn advocated a "straight cut" from the Milwaukee River near the Menomonee River confluence out to Lake Michigan. This channel was made in 1857 and is still in use today. Prior to that, the natural outlet for all three rivers was at the southern end of Jones Island where the Kinnickinnic now turns north to flow out of the straight cut. This area was later filled to provide railroad access.