From Soaking Wet to Very Big Business

It's 1990, and Ian Brownlee, out walking his dog, meets a man whose visa application he had refused just that very morning. The man is about to swim across the river to his probable death, so Ian advises him of a much safer spot to cross, about 200 yards thataway. These are the old days of immigration. When and how did immigration become a multibillion dollar business and a hot-button in domestic politics?  Ian is the expert.