Americans celebrate 250th Fourth of July with fireworks and travel surge

Communities across the country are marking America's 250th birthday with fireworks, celebrations and a surge in holiday travel despite dangerous summer heat.

(NBC)- Communities across the country are marking America’s 250th birthday with fireworks, celebrations and a surge in holiday travel despite dangerous summer heat.

Patriotic displays are appearing nationwide, from a giant “250” mowed into a North Carolina lawn to a human Liberty Bell formation in Philadelphia.

Boston kicked off the festivities with an early fireworks show, while New York welcomed a fleet of tall ships and finalized preparations for its annual display. In Washington, D.C., crews completed preparations for what organizers say will be the world’s largest fireworks show as part of the Freedom 250 “Salute to America” celebration on the National Mall.

President Donald Trump is expected to speak during the event, which was delayed from 1 p.m. to 5 p.m. because of triple-digit temperatures. Officials are urging attendees to stay hydrated as extreme heat continues to affect much of the East Coast.

The dangerous conditions have already led to heat-related medical emergencies, including in Berks County, Pennsylvania, where first responders treated numerous people during outdoor events.

Despite the weather, holiday travel remains strong. Storms in the South caused flight delays, while extreme heat disrupted some rail service because of overheated tracks.

AAA estimates more than 72 million Americans will travel during the Independence Day holiday, making it one of the busiest Fourth of July travel periods on record.