CHICAGO (WLS) -- Flooding is the number one severe weather killer nationwide, and the Midwest is no stranger to extreme flooding events. Major flash flooding and record-setting rainfall most recently hit the Chicago-area in May 2020. In just four days, more than 7 inches of rain fell, contributing to major flooding on roadways. On Lower Wacker Drive, several people and trapped motorists had to be rescued by boat. The Chicago River rose high enough that the Metropolitan Water Reclamation District had to reverse the flow to Lake Michigan. May 2020 was the wettest May in Chicago history, with 9.5 inches of rainfall. It was also the third consecutive year with record rainfall in May. Additionally, two of the last five years overall were some of our wettest on record.