The Mississippi River is known as the Middle Mississippi from the Upper Mississippi River's confluence with the Missouri River at St. Louis, Missouri, for 190 miles (310 km) to its confluence with the Ohio River at Cairo, Illinois. The Middle Mississippi is relatively free-flowing.
As Hopper notes, eight major U.S. airlines offer free cancellation for tickets purchased at least seven days in advance: Delta, United, US Airways, JetBlue, Southwest, Spirit, Frontier and American (in American 's case, you'll hold your ticket instead of purchasing it).
Depending on your fare type, you may be able to cancel your flight.*. If your Qantas flight booking or Frequent Flyer Reward booking was made online at qantas.com or through a Qantas Contact Centre in Australia, United Kingdom, New Zealand, Singapore, United States, Mexico, Chile and Argentina, you may be able to cancel online.