THE WEST LOOP in Chicago was once the city’s meatpacking district. That is long gone, but the neighbourhood is still a place where people come from miles around to buy beef. At Au Cheval, a fancy burger joint where tourists queue up for hours, the signature dish is a double cheeseburger served with a fried egg. It is reputed, at least among Chicagoans, to be the best burger in the world. Yet the price of such a delight is rising. It is not only that eggs now sell for $6 a dozen, thanks to bird flu. More quietly, beef has been rising in price for years now too. And thanks to Donald Trump’s proposed tariffs, it may be about to get much worse.