Chicago and New York City has MORE " urban sprawl ", because of immigration, since 1970 ? Not that I know about. Chicago's " sprawl ", since 1970, has been upwardly mobile and empyt-nester fed. So has New York's been. The gentrification of both Chicago and all five boroughs of N.Y.C.,still has most immigrants, legal and otherwise,living in slums, just as they did in the early part of the 20th century and before.
No, actually, I take that last bit away. Slums were built and expanded upon, in Manhattan, in the mid to late parts of the 19th century, so, yes, immigrants did, indeed, add to Manhattan's " urban sprawl "; just NOT since 1970!