As to why might imports to the Midwest might be growing faster than other regions, she ventures that part of the answer could be related to increasing global trade flows and the growing US domestic shipping market creating demand for regional distribution centers located closer to customers. For example, she notes, FedEx is significantly expanding its operations in Indianapolis and Ohio as part of a multi-billion dollar plan to nearly double its daily North American package volume capacity. In addition, markets such as St. Louis, Kansas City, MO and Indianapolis have well-developed transportation infrastructures with extensive rail and highway connections as well as an inland waterway system, making the movement of goods easier and faster.

"The rapid growth of the manufactured goods exported from the Midwest, such as autos, farming equipment, and machinery could also be behind the increase," she suggests. "On a national level, exports explain less variation in warehouse demand than imports do, but we should remember that the Midwest is known as the nation's manufacturing hub."

As Suran points out, manufactured exports to other countries are booming thanks to the falling dollar and strong global growth. Furthermore, many US-made goods contain parts made in other countries. Ford and GM cars, for example, contain components produced from China to India or Mexico, meaning that the Midwest needs to import more in order to export more.