Despite inflation and memories of past holiday travel meltdowns, no fewer than 55.4 million people are expected to hit airports and highways in the United States alone, in what has been dubbed the world busiest week in recent time.

The busiest days for flights were Tuesday and Wednesday as well as the Sunday after Thanksgiving.The Transportation Security Administration was expected to screen 2.6 million passengers on Tuesday and 2.7 million passengers on Wednesday. Sunday will draw the largest crowds with an estimated 2.9 million passengers, which would narrowly eclipse a record set on June 30.

Meanwhile, AAA forecasts that 55.4 million Americans will travel at least 50 miles (80 kilometers) from home between next Wednesday and the Sunday after Thanksgiving, with roads likely to be the most clogged on Wednesday.

The weather could snarl air and road traffic. A storm system was expected to move from the southern Plains to the Northeast on Tuesday and Wednesday. Parts of Maine, Vermont and northern New Hampshire are expected to get 3 to 7 inches (7 to 17 centimeters) of snow between Tuesday night and Wednesday.

U.S. Transportation Secretary, Pete Buttigieg, said during a news conference Monday that the government has tried to better prepare for holiday travel by hiring more air traffic controllers, opening new air routes along the East Coast and providing grants to airports for snowplows and deicing equipment.

He warned travellers to check road conditions and flight times before leaving home. “Mother Nature, of course, is the X factor in all of this,” he said.