Though this is well within the margin of error , List of United States cities by population uses the 2008 estimates for purposes of ranking .
^ a : The US Census estimated that Worcester surpassed Providence in 2006 by 199 people .
Though this is well within the margin of error , List of US   cities by population uses the 2008 estimates for purposes of ranking .
^ a : The US Census estimated that Worcester surpassed Providence in 2006 by 199 people .