A record-setting 72.2 million Americans are expected to travel for the Fourth of July holiday this year, the most ever recorded for Independence Day. 

The increase is fueled by strong demand for summer travel, lower gas and airfare prices, and a favorable calendar. With the holiday falling on a Friday, many travelers are taking advantage of the long weekend to extend their vacations.

"It has been a very long day and long night. We haven't slept," said one traveler trying to navigate the crowds at a major airport terminal.

AAA reports that more than 61 million people will travel by car, and nearly 6 million will fly between June 28 and July 6.

Thursday, July 3 was forecasted to be the busiest departure day. Tuesday, July 8 is expected to be the lightest travel day and the most affordable for return flights, according to data from travel booking sites.

The National Weather Service says dangerous heat is affecting large portions of the Midwest. Heat advisories are in effect in Minnesota and Wisconsin, where temperatures are running 10 to 20 degrees above average and heat index values are nearing 100 degrees.

Triple-digit temperatures are also forecast in parts of Texas through the weekend. Health officials are urging travelers to protect themselves from the high heat.

"Let's do it smartly," said Dr. Glenn Barnes of A&M College of Nursing. "Make sure they have proper clothing, sunscreen, and bug repellent."

While much of the country will see clear skies for fireworks, the Southeast is dealing with widespread rain and the threat of tropical weather. A disturbance off the coast of Florida could develop into a tropical storm, bringing gusty winds and heavy rain along the Gulf Coast.

Parts of Florida, southern Georgia, and coastal Alabama may receive two to four inches of rain through Friday, with localized totals reaching six inches. That could create travel delays on major highways and at regional airports.

Further west, monsoonal moisture is producing downpours in Texas, Arizona, and New Mexico.

Red flag warnings have been issued in Oregon, Idaho, Utah, and Nevada due to dry and windy conditions. In California, fire crews are responding to multiple small wildfires sparked by the heat and low humidity.

With historic travel volumes and weather threats in play, officials are urging Americans to plan ahead, and monitor forecasts as they celebrate the holiday.