Flooding in the Midwest Tuesday shut down portions of two interstates and threatened hundreds of homes, the Associated Press reports. At least 18 people have been killed. South of St. Louis, the Mississippi river, swollen after days of torrential rain, is expected to crest at record levels later this week.

[A leaky BP oil rig in the Gulf of Mexico "could equal or even eclipse" the damage caused by the 1989 Exxon Valdez spill. Experts expect the slick could hit the Mississippi River Delta by late tonight. Image via Getty.]