More than a million customers in the storm-hit United States remained without power Wednesday, as canceled firework displays and no air-conditioning made for a miserable July 4 holiday for many Americans.

A fierce band of thunderstorms, packing hurricane force winds, tore across the country on Friday, wreaking havoc from Illinois to Ohio to Kentucky, and causing particularly widespread destruction in and around the capital Washington.

Falling trees snapped power lines and companies struggled to get power back to many families, sweating again in sweltering conditions on Wednesday as the mercury soared back above 90 degrees Fahrenheit (32 degrees Celsius).

West Virginia, one of nine states impacted by the inclement weather, had the highest number of customers without power at roughly 317,000, according to a release from the US Department of Energy Wednesday morning.

Some 20 deaths are attributed to the weather.

Traditional barbeque events had to be re-arranged as partygoers looked for respite in cooling shelters.

The National Weather Service, meanwhile, warned of large hail and damaging winds in the Great Lakes region, especially in northern Minnesota, potentially throwing a wrench into festivities there.

In Chicago, the sizzling heat could make this year's holiday the hottest in a century.

Elsewhere, in arid areas such as the western state of Colorado where wildfires have been raging, community firework celebrations, an annual draw for young and old alike, were scrapped to avoid sparking more blazes that have left hundreds homeless.

The election heat was also intensifying as President Barack Obama and Republican rival Mitt Romney sought to capitalize on the patriotic undertones of the day, which marks the 236th year of independence from British rule.

Obama held a naturalization ceremony for active duty members in the White House mid-morning and was expected to host a barbeque complete with a concert and fireworks later in the day.

"No other nation constantly renews itself, refreshes itself with the hopes, and the drive, and the optimism, and the dynamism of each new generation of immigrants," Obama told the group.

His speech to people who had immigrated from as far afield as Guatemala, Nigeria and Ukraine was a clear nod to a recent shift in his administration's immigration policy that could help the Democrat secure a second term.

"You're one of the reasons why, even after two centuries, America is always young, always looking to the future, always confident that our greatest days are still to come," Obama said.

Romney, taking a week off to spend time with his family at an upscale lakeside property in Wolfeboro, New Hampshire, was due to participate in a parade in the New England town as cameras rolled.

"As we gather to enjoy food and fireworks, let us also take a moment to pay tribute to the patriots who signed the Declaration of Independence -- and the brave men and women who have fought to protect our freedoms through every generation that has followed," he said in a statement.

"With so many around the world still consigned to tyranny, the Fourth of July is a time to appreciate the blessing of liberty and be thankful that we are Americans."

Despite the dire scenarios faced by many, large scale celebrations were still going forward in cities like New York and Boston where singer Jennifer Hudson was set to perform.

Headlines of quirky Fourth of July traditions also were not to be missed.

An annual hotdog-eating competition in New York, for one, saw Sonya "The Black Widow" Thomas successfully defend her title after setting a new world record by downing 45 frankfurters.

Thomas' male counterpart, Joey "Jaws" chestnut, crammed 68 hot dogs down his throat, matching his 2009 record.