The latest developments on flooding in the Midwest (all times local):

1:30 a.m.

Crews are trying to keep a major interstate highway south of St. Louis open amid historic flooding.

The Missouri Department of Transportation said Wednesday night that I-55 at the Meramec River near Arnold could close overnight or Thursday.

An aggressive sandbagging operation was underway to keep the highway from closing. Other connections between St. Louis and Jefferson counties already are closed, including I-44 over the river.

Local media report the traffic has been rerouted. But a spokeswoman for the Department of Transportation told the St. Louis Post-Dispatch (http://bit.ly/1YTOKkk ) the detours are temporary to move in more equipment for flood-fighting.

Marie Elliott says, "The goal is to keep the highway open."