What american cities United Airlines link from Miami in DIRECT flight

What american cities United Airlines link from Miami in DIRECT flight?
My parents have a free trip inside USA because of mileage plus. They plan to take it in january. My mum wants something not cold so I thought about Los Angeles but the flight is not direct from Miami. They are old and they prefer a direct flight. On United web site, I coudn't see what are the direct flights from Miami.
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1 :
According to their most recent timetable, United offers nonstop flights from Miami to Chicago O'Hare, Denver, Orlando, Tampa, and Washington, DC. They also may wish to consider using their Mileage Plus miles for a free trip on US Airways (which is allowed, as a Star Alliance partner, for the same amount of miles) -- US Airways flies nonstop from Miami to Pittsburgh, Charlotte, Philadelphia, and Las Vegas.
2 :
see: http://www.united.com/page/middlepage/0,6823,1019,00.html
3 :
Usually the "hub" airports of United had direct flights to and from Miami. (Like, Philadelphia, Chicago, Baltimore, and Las Angelas.) Go on united.com, and you'll find the information.