The New York Times has a searchable list of the 5000 most common surnames in the US, based on data from the 2000 US Census. Not surprisingly, the highest names that jumped more than 10 spaces from the previous decade's ranking were Hispanic: Garcia went from 18th to eighth; Rodriguez from 22nd to ninth; and Hernandez from 29th to 15th. Other big movers included Nguyen (229th to 57th) and, for some reason, Myers (from 101st to 85th). But Smith still seems to have a firm grasp on first place: There were 881 occurences of the name for every 100,000 people, well ahead of second-place Johnson (688 per 100,000).
Currently, the most-represented name on the roster of the US Congress is Davis (seven members), which ranked seventh among the general population. Among names worn at least three members of Congress, Bishop ranks the lowest (238th) on the Census list. Does that mean a clerical-sounding name is an advantage in American politics? The most common surnames that don't appear on the congressional roster are Williams, Garcia, and Rodriguez.
Copley is among the names that seem headed for an exit from the list; it dropped from 3670th to 4973th in a single decade.