In New York, throngs are expected to watch the annual Macy's fireworks blowout and the Nathan's Famous frankfurter- chomping contest on Coney Island on July Fourth.
In Washington, President Donald Trump is observing his first Independence Day in office by hosting a White House picnic for military families, followed by a fireworks viewing event for military families and staffers.
In Boston, one of 14 original copies of the Declaration of Independence will be displayed at a museum, and hundreds of thousands of people are expected at the city's fireworks show. Organizers of Chicago's Independence Day celebration are expecting such large crowds that the city's Navy Pier is opening at 10 am, nearly 12 hours before fireworks begin.
For all the pomp and celebration, July 4 arrives with Americans deeply split over the nation's direction, after last year's presidential election and political clashes over immigration, health care and other issues in the early months of Trump's Republican administration.
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And in an era of concerns about security, the Independence Day celebrations are mixed with precautions. The New York Police Department planned to station 100 vehicles to block intersections and 20 sand-filled sanitation trucks to fortify viewing areas for the Macy's fireworks show.
Boston police also plan to put trucks and other heavy equipment near the celebration there. Police in both cities say there are no confirmed threats.
In a somber observance of the toll of terror, small American flags will be placed by all the nearly 3,000 names on the National September 11 Memorial in New York.
Meanwhile, residents of Laconia, New Hampshire, might not have had a Fourth of July parade if a resident hadn't stepped in to organize it after learning it was facing cancellation for lack of interest. Some 25 organisations have since signed up to provide floats or marchers.