This is a joint post with Charles Kenny
Zambia and Ghana are the 27th and 28th countries the World Bank has reclassified as middle-income since the year 2000
Doctors perform cataract surgery at the Lusaka Eye Hospital in Zambia. It's inexpensive and it changes people's lives instantly, so it's a good example of how just a little bit more money can make a huge difference to the world's poorest people. Photograph: Per-Anders Pettersson/Getty Images
Remember the poverty trap? Countries stuck in destitution because of weak institutions put in place by colonial overlords, or because of climates that foster disease, or geographies that limit access to global markets, or simply by the fact that poverty is overwhelmingly self-perpetuating. Apparently the trap can be escaped.