You'd probably need to have Clay lose the 1844 election. He's the one who got that southern industry going, after all-- even if it was a bit of a clenched-teeth compromise. He wanted to implement his American System without favour for any region, but when it became clear that he'd never get any of it past Congress without southern support, he eventually agreed to cater to southern interest. What was it again? Nearly two thirds of the increased revenue from higher tarriffs spent to develop southern industry during Clay's eight years? I know, those numbers are disputed, but it wasn't that much lower-- although things of course evened out after Frelinghuysen succeeded Clay in '52. But by then, the south'd had its impetus, and wealthy southernerns had gotten a taste of the textile profits...
Anyway, '44 was a close call. Just have Polk win, and that'll probably do the trick.