Opponents of Prince William County's plan to target illegal immigrants tried marches, a boycott and a one-day strike. They organized protest caravans with hundreds of cars and turned out ever-larger crowds for county board meetings. When the plan went before supervisors for a vote Oct. 16, scores of Hispanic residents lined up to deliver tearful, urgent testimony...All the supervisors...voted to push ahead with the measures anyway. The clash over illegal immigration in Prince William has placed several cultural differences on display...But perhaps none was as stark as the two competing political strategies...one rooted in a tradition of street protests, the...