Over the course of this year, hundreds of thousands of laborers from around the world will be invited to our shores as guest workers. They will come in search of economic opportunity, or for a summer job and an adventure. As the debate over immigration rages on, these men and women will pick our fruits and vegetables, mow our lawns, care for our children and clean our homes. They will be here legally, as guests of the United States government, under temporary work visas programs that have existed for decades and grown steadily over that time.