Two people died on Thursday after a helicopter they were on board crashed into a barge on the Mississippi River, shutting the waterway to traffic near Alton, Illinois, the U.S. Coast Guard said.

The Coast Guard had intended to decommission its MH-65 Dolphin helicopter fleet, in use since 1984, replacing it with the MH-60 Jayhawk, largely because the platforms had reached the end of their ...