E-commerce has more than doubled the average footprint of warehouses built in the United States since the early 2000s, with the largest expansions coming in metro areas, according to a new report from CBRE Group, Los Angeles.

CBRE analyzed the average size of warehouses built in the United States during the last development upswing from 2002-2007 and compared those figures to the current building period of 2012-2017. The analysis found that the average size increased by 143% to 184,693 square feet and the average warehouse clear height rose by 3.7 feet, to 32.3 feet in total.

“This dramatic expansion of warehouse size and height in the U.S. is almost purely a product of e-commerce, which has created demand for massive warehouses with high ceilings to store extensive, fast-moving inventories,” says David Egan, global head of industrial and logistics research. “This demand is a long-term factor, meaning that U.S. markets without enough modern logistics facilities will see continued construction as they catch up.”

The largest gains in average warehouse size came in markets with big, growing populations and a ready supply of developable land, led by Atlanta (284% gain in average size), Cincinnati (237%) and California’s Inland Empire (222%).