WINNIPEG -- A Prairie trucking company that once grew on the back of the U.S. economy is now buckling because of struggling markets south of the border.

Winnipeg Motor Express filed for creditor protection last month after struggling with negative market forces like the price of fuel, dwindling U.S. exports, and the Canada-U.S. exchange rate, reports the Winnipeg Free Press.

Formerly a subsidiary of the Ram Group of Companies, the 15-year-old carrier had about 250 power units and 400 trailers a few years ago.

According to the newspaper, the carrier received an extension to its protection order until July 31.

The company is continuing to operate while reportedly searching for a new buyer.

The company is said to be loaded with debt and was poorly positioned to weather the so-called perfect storm that has rained down on trucking since 2004.

Winnipeg Motor Express derived about 70 percent of its revenue from U.S. business. That market has severely dried up in recent years.

Taking advantage of the goods-sorting hub that is Winnipeg, the company established itself as a major cross-border hauler of agricultural and foodstuffs. It expanded from its origins as a consolidator and courier in the Prairies and took on long-distance truckload freight, triangulating routes from Manitoba down the I-29 and I-35 corridor to Texas, and back north to cities in Western Canada before returning home.

Rob McMahon, a senior vice-president of Ernst & Young in Winnipeg, has been appointed court-appointed monitor for WME, the Free Press reports.