From NBC's Pete Williams and Domenico Montanaro
As the inaugural concert continues with a crowd some estimates show to be about 750,000, a Secret Service spokesman says Sunday has unfolded with no security problems.
Teams responded to a few reports of suspicious packages, which have become routine at events like this, but all turned out to be nothing.
The concert so far has seen a wide array of Hollywood stars and singers, including U2, which is singing now. There have been a variety quotes from American presidents, particularly Lincoln. After all, the concert is taking place at his memorial.
The Obamas are sitting front row, stage right, with the Bidens next to them.
Themes so far, not surprisingly have been "change" as well as togetherness and service. Service is something Obama has stressed, and designated tomorrow, Martin Luther King Jr.'s birthday, a national day of service.
The concert opened with Bruce Springsteen playing The Rising backed by a gospel choir. It has seen an eclectic mix. There was Shakira singing with Usher and Stevie Wonder, Sheryl Crow with will.i.am, and others.
Celebrity speakers have been aplenty, including Samuel L. Jackson, Tom Hanks, Tiger Woods, Jamie Foxx, Steve Carell, Laura Linney and several others. The most political so far, also not surprisingly, was Bono.