Across the United States, Americans are celebrating the Independence Day holiday with picnics, fireworks, and a sense of caution. Festivities in the U.S. capital are scheduled to include a concert and fireworks display over the Washington Monument. Severe weather earlier Wednesday forced police to evacuate the National Mall - the large open park area east and west of the monument. Authorities began allowing the crowds to return shortly after the rain cleared out, and the evening's activities are scheduled to continue as planned. VOA's Paula Wolfson reports in large cities, like Washington D.C., security is tight for the Fourth of July festivities.

The threat of terrorism was on President Bush's mind as he delivered a holiday speech to military personnel and their families in the state of West Virginia.

President Bush during his visit to West Virginia Air National Guard 167th Airlift Wing, in Martinsburg, W.V., 04 Jul 2007

"We must succeed for our own sake," he said. "For the security of our citizens we must support our troops. We must support the Iraqi government and we must defeat al-Qaida in Iraq."

The president defended his Iraq strategy, and praised those who are serving in the U.S. military during difficult times.

"In this war against radicals and extremists, in this war on terror, you are showing that the courage that won our independence more than two centuries ago is alive and well here in West Virginia," said Mr. Bush.

The holiday marks the 231st anniversary of the United States declaring its independence from Britain.

4th of July parade in Anchorage, Alaska

Mr. Bush returned to the White House after the speech, where he will watch the traditional holiday fireworks with friends and family.

Hundreds of thousands of visitors are expected to take part in the celebrations in the nation's capital, and extra security precautions are in place.

Security has been tight on the Fourth of July holiday since the September 11, 2001 attacks on the United States. This year, Independence Day follows a series of attempted attacks in the United Kingdom, prompting local authorities to increase the police presence at major events.