The Diversity Visa lottery has been an incredibly successful policy, beyond the expectations or even the intentions of its creators. Since 1995 it has diversified the source countries of immigrants to the United States. In particular it has brought in more immigrants from African countries that historically were restricted from sending many immigrants to the U.S.

It is a small program — it issues about 50,000 immigrant visas annually in a system that each year admits about one million lawful permanent residents — that packs a big punch.