Obamacare gave Americans a lot to argue about before it became law in 2010. One contentious question concerned its eventual economic effect, with supporters saying it would invigorate businesses by freeing them from burdensome healthcare costs and opponents warning of a drag produced by tax increases and government bureaucracy. A decade’s worth of data has now rendered a partial verdict: states that have fully embraced the Affordable Care Act are enjoying healthier labour markets and stronger income growth than those that haven’t...