Answer: The problem with illegal immigrants in Springfield was solved by Mayor Quimby putting forth Proposition 24, which was a vote to deport all illegal immigrants. The town is divided, and Marge defends the immigrants by saying, “And really, your only crime was violating U.S. law.” Homer eventually supports the immigrants as well, giving this final and eloquent speech:
“If I could just say a few words, I’d be a better public speaker. [pause] Now that you’re all relaxed… Most of us here were born in America. We take this country for granted; but not immigrants like Apu. While the rest of us are drinking ourselves stupid, they’re driving the cabs that get us home safely, they’re writing the operas that entertain us everyday, they’re training our tigers and kicking our extra points. These people are the glue that holds together the gears of our society. If we pass Proposition 24, we’ll be losing some of the truest Americans of all.”
The proposition passed overwhelmingly, and all illegal immigrants were deported. Apu got his citizenship via a grandfather clause granting amnesty to long-time illegal residents, and all the citizens were happy (except Willy, who got deported). This is yet another problem solved by The Simpsons.