Washington ? America changes course today.

Barack Obama of Illinois will take office as the nation’s 44th president at 11 a.m. CST in a simple yet elegant ceremony that will mark a peaceful transfer of power. He does so at a time of unusual peril, with a sputtering economy at home and U.S. troops still in harm’s way in Iraq and Afghanistan.

The inauguration of the youthful and popular new president — and the departure of the unpopular incumbent, George W. Bush — will set off a potentially dramatic shift in direction on policies, from the wars abroad to the role of the federal government at home, and a change in tone, with the rise of a new generation more prone to problem-solving than to ideological conflict.

At the center of it all is the 47-year-old son of a black father from Kenya and a white mother from Kansas who’ll become the first African-American to reach the nation’s highest office.

Thousands of people poured onto the National Mall on Monday, spreading a festive mood across the capital among those eagerly anticipating not only the swearing-in ceremony and the inaugural parade but also the start of a new era. They were the vanguard of what’s likely to be a million-plus throng there today. Estimates of how many people are flocking to Washington run to 3 million.

Obama heads to the White House with the great hopes and patient optimism of the American people, according to a new McClatchy-Ipsos Poll. It offers a stark contrast to the crisis of confidence in the economy and government that’s gripped the country in recent months.

Obama spent Monday, his last day as a private citizen before taking office, in symbolic gestures meant to highlight the deeds of others, including a visit with wounded soldiers at the Walter Reed Army Medical Center, working with volunteers at a Washington shelter for homeless teens and attending a dinner honoring his Republican rival for the presidency, Sen. John McCain of Arizona.

“We can accomplish anything,” Obama said at the homeless shelter, showing support for volunteer work on the day set aside to commemorate the 80th anniversary of the birth of Dr. Martin Luther King Jr.

“One of the goals of my administration will be to make sure that we have a government that’s more responsive and more effective and more efficient at helping families. But don’t underestimate the power for people to pull together and to accomplish amazing things. …

“Given the crisis that we’re in and the hardships that so many people are going through, we can’t allow any idle hands. Everybody’s got to be involved. Everybody’s going to have to pitch in, and I think the American people are ready for that.”

Nearly two out of three Americans already are feeling better about the country with Obama taking office, according to the McClatchy-Ipsos Poll released Monday. The same number think that he can improve the economy.