JUDY WOODRUFF:

But, first: a bloody year in Chicago. And residents, police and community leaders are asking why the violence is getting worse, instead of better?

It is already the deadliest year in more than two decades, 500 homicides so far, 90 in August alone. The killings were mostly clustered on the city's South and West Sides.

John Yang went to Chicago to try to find out why, despite calls for new action, the violence there is so hard to rein in.