Crowds fill O’Hare International Airport in Chicago on Wednesday. (Tannen Maury/EPA-EFE/REX/Shutterstock)

Rain, snow and winds across the United States are disrupting travel on one of the busiest days of the year and threatening to keep Thanksgiving Day parade balloons from flying.

Two large storms are causing widespread travel problems as close to 55 million people are expected to take to the roads and air, according to the AAA website. Areas around Denver, Colorado, received 8 to 12 inches of snow, causing treacherous road conditions, accidents, closures and the cancellation of almost 500 flights Wednesday.

In New York City, winds could reach 25 miles per hour (mph) on Thursday, threatening to ground the massive balloons traditional to the Macy’s Thanksgiving Day Parade.

New York has regulations that have been in place since 1997 that will determine whether the balloons, which can be as high as 60 feet and are handled by ground crews holding ropes, will be allowed to fly. The rules ban flight in sustained winds of 23 mph, or with gusts of 34 mph, according to the New York Times.

— Bloomberg News