When the U.S. economy emerged from the recession in June 2009, productivity was rising at a fast clip. Companies had spent the downturn cutting jobs and were lean and efficient. Productivity—output per hour worked—jumped 5.5 percent in the fourth quarter from a year earlier as workers did more with less. But as the recovery has chugged on, productivity growth has stalled, averaging less than 1 percent a year since 2011. Workers were actually less efficient in the first quarter of 2014, producing fewer goods and services per hour than they had during the previous quarter.

Retail space isn't what it used to be. More people are browsing and buying online. Stores can get products faster from manufacturers, so they don't need as much space to warehouse inventory. Small businesses are thus moving to smaller storefronts to lower costs.

The Japanese government has long banned most weapons exports. That policy helped buttress Japan's pacifism, but it also hindered the growth of the country's defense industry. Because it couldn't sell parts overseas, Japanese defense companies missed out on chances to develop fighter jets, tanks and other weaponry with the U.S. That's changing.

Chinese companies are on a North American buying spree, investing $14bn in the U.S. last year, a record high, says a new report by New York's Rhodium Group.