Treasury Secretary Steven Mnuchin, right, and his wife, Louise Linton, hold up a sheet of new $1 bills on Nov. 15 at the Bureau of Engraving and Printing in Washington. (Jacquelyn Martin/AP)

The wealthiest 1 percent of American households own 40 percent of the country's wealth, according to a new paper by economist Edward N. Wolff. That share is higher than it has been at any point since at least 1962, according to Wolff's data, which comes from the federal Survey of Consumer Finances.

From 2013, the share of wealth owned by the 1 percent shot up by nearly three percentage points. Wealth owned by the bottom 90 percent, meanwhile, fell over the same period. Today, the top 1 percent of households own more wealth than the bottom 90 percent combined. That gap, between the ultrawealthy and everyone else, has only become wider in the past several decades.

Let's talk a bit about that wealth gap. Wealth, often described as net worth, describes how much stuff you actually have: It's the value of your assets minus the value of your debts. If you have a $250,000 house but you still owe $200,000 to the bank on it, and you have no other debts or financial assets, that means your net worth is $50,000.