Organizers for the Democratic National Convention say they now expect some 50,000 people to come to Denver for the event this August.
That number is more than 40 percent higher than the original estimates.
A spokeswoman for the Democratic Nationals Convention Committee says overwhelming interest in the potentially historic event has driven up the expected participation.
City officials say they are relying on convention organizers for the estimated number of participants, but they hope the increase will mean a larger economic boon for Denver and Colorado than they first anticipated. Estimates for the region's financial gain exceed 150 (M) million dollars.
Katherine Archuleta, the mayor's convention liaison, says the increased estimates are not expected to affect planning or security preparations for the convention.