More Americans filed for their first week of jobless benefits last week, marking the seventh straight week in which more than 400,000 people have been added to the unemployment rolls. In the week ended May 21, 424,000 Americans filed for their first week of unemployment benefits, the Labor Department said Thursday. That marked an increase of 10,000 from the revised 414,000 initial claims filed the week before, and was significantly more than the 400,000 claims economists had expected for the week.