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.or example, if you book a ticket on United at 8 p.m., you have until 8 p.m. the next day to cancel the ticket and get a full refund. Under this policy, you can also make changes to your flights within 24 hours of booking and not pay a change fee.