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).
When you purchase a refundable ticket on United Airlines, you can cancel your flight at any time without paying a penalty. You will get a full refund for the original ticket price.Keep in mind that refundable tickets often cost a lot more than nonrefundable tickets.nited Airlines has a 24-hour flexible booking policy that allows for a full refund of the fare if a ticket is cancelled or changed within 24 hours of booking.