The Chicago River was once so polluted that a reporter described it as "green at the sausage factory, blue at the soap factory, and yellow at the tannery." Its banks hosted vice dens built on shifting sand, a Civil War-era submarine nicknamed the "Fool Killer," and the worst inland maritime disaster in American history: the 1915 capsizing of the SS Eastland, which killed 844 people in minutes while the vessel was still moored to the dock.

What saved the river was a feat of audacious engineering: in 1900, its flow was reversed entirely, sending pollution away from Lake Michigan. Today kayakers paddle where sewage once caught fire.

VoiceMap's self-guided audio tours trace two centuries of the river's history, from its Pottawatomie past through steamboat wrecks, corrupt bridge keepers, and underground freight tunnels, connecting the city's industrial ambition to the waterway that made it possible.