Polk St. Tower was located at the south end of Rock Island's LaSalle St. Station in downtown Chicago. It controlled the trackage coming into the stub ended station. Rock Island was handling commuter trains and still had the "Quad Cities" and "Peorian" intercity trains since they did not join Amtrak. By 1976 those trains were called the "Quad Cities Rocket" & "Peoria Rocket". They were discontinued in 1977, but Metro still runs commuter trains from this station. The tower is no longer here.
