By Paul Krugman, Op-Ed Columnist — August 24, 2014

Gov. Rick Perry of Texas is running for president again. What are his chances? Will he once again become a punch line? I have absolutely no idea. This isn’t a horse-race column.

What I’d like to do, instead, is take advantage of Mr. Perry’s ambitions to talk about one of my favorite subjects: interregional differences in economic and population growth.

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