DENVER – Western Distributing Transportation Corp., one of Colorado's largest trucking companies, has reportedly been licensing most of its fleet out of state for 13 years to avoid paying Colorado sales taxes and emissions fees, according to 9news.com. While the signs on the truck doors say Denver, Colorado, their license plates say Wyoming.

According to the Colorado Motor Carriers Association, it cost $11,749 for a new truck tractor in Colorado, or twice as much as Wyoming, which cost $5,559. The association also claims that Colorado has the highest sales tax of any surrounding state, reported 9news.com.

The practice by Western Distributing Transportation Corp. has cost Colorado millions of dollars in sales tax during the state's worst budget crisis in decades, according to a 9 Wants to Know investigation.

Western Distributing opened for business in 1933 and maintains a fleet of 235 trucks and 345 trailers at its Denver headquarters. Records show the company's trucks drove 4.5 million miles on Colorado roads last year and 1.5 million miles in Wyoming, reported 9news.com.

House Speaker Terrance Carroll (D-Denver) disapproves of the practice. "That's an insult to the all of the businesses that do what they have to do in Colorado," he said, according to 9news.com.

Western Distributing says trucking regulations put forth by the International Registration Plan (IRP) allow them to license their vehicles in Wyoming. IRP requires companies have a real place of business in the state that they register vehicles, complete with a permanent employee, a building, and company records.

The trucking company stopped paying Colorado sales tax on its interstate tractor trucks in 1996 when it began licensing its fleet in the state of Nebraska. In 2006, Nebraska reportedly kicked the company out of the state after an audit found it did not have an actual established place of business there, according to 9news.com.

After leaving Nebraska in 2006, Western Distributing began registering its fleet in Wyoming instead of Colorado.