You wouldn’t ever put your $1,000 flat screen in the freezer, but you’re doing essentially the same thing if you are moving it across the country in the wintertime, especially if you leave it in the vehicle overnight.
LCD screens are made of liquid cells, liquid that freezes. For this reason many TV maintenance manuals tell you to keep your TV between certain temperatures, usually above 40 degrees. Using your TV in colder temperature can result in permanent problems, notably with the functioning of the screen.
However, just because you shouldn’t use your TV in freezing temperatures doesn’t mean you can’t move it in these temperatures. All you need to do is give your TV time to warm back up to acceptable temperatures. 24 hours will usually be enough, but give it two days to be on the safe side if temperatures were especially cold during the move or if your TV is especially large.