By Karen Brooks AUSTIN, Texas (Reuters) - A deadly winter storm some forecasters say is the worst to hit the United States in years slammed the nation's midsection Friday, snarling travel and knocking out power for hundreds of thousands of customers. The line of ice, snow and freezing temperatures stretched from the Texas-Mexico border northeast to the Ohio Valley, with the most severe conditions near Dallas, then punching through Arkansas and western Kentucky, according to forecasters at AccuWeather.com. First-time air traveler Madison Cunningham, 18, was stranded for more than 12 hours overnight in the Dallas-Forth Worth International Airport when ice prevented her flight home to Indianapolis. "I'll take the train next time." The travel troubles also delayed commerce, as the United Parcel Service, the nation's largest package delivery company, said deliveries have been disrupted in Arkansas, Missouri, New Mexico and the panhandle portion of Texas on Friday.