Otero has shown his work in solo exhibitions at the Chicago Cultural Center (2010), Kavi Gupta (2009), the Contemporary Art Workshop Gallery (2008), and the Union League Club of Chicago (2008).
Warren was also a member of the Michigan Historical Society, the Chicago Historical Society, the Wisconsin Archaeological Society, the Union League Club, and the Geographic Society of Chicago.
He was a Director of the Irving National Bank, and a member of the following clubs: Down-Town Club of New York, the Union League Club of Brooklyn, the New York, Larchmont, and Atlantic Yacht clubs, the Union League Club of Chicago, the Metropolitan Museum of Art, the American Geographical Society, the Arctic Club of New York, and the Caughnawaga Hunting and Fishing Club of Quebec.
Chicago | Soviet Union | Major League Baseball | National Football League | European Union | University of Chicago | Union Army | National Hockey League | rugby union | UEFA Champions League | Chicago Tribune | Union | Premier League | Australian Football League | rugby league | Major League Soccer | Chicago Cubs | Chicago White Sox | National League | League of Nations | Chicago Bears | UEFA Europa League | Art Institute of Chicago | American League | Canadian Football League | Arena Football League | the Football League | International Telecommunication Union | American Hockey League | trade union |