A federal anti-terrorism program that will take effect in late 2006 will require truck drivers to prove they are legal U.S. residents. Undocumented drivers currently make up as many as half of the port-trucking workforce nationwide, according to Michael Belzer, professor of industrial relations here. Belzer wrote a book, titled "Sweatshops on Wheels," about adverse results of the de-unionization of the trucking industry. Many illegal drivers carry false Social Security numbers or work under assumed names. The story is on today's front page.