It cost hundreds of millions of dollars to develop and quickly found favor with the freight railroads when it was introduced in 2005.

GE Transportation’s Evolution locomotive, Erie’s top export, marked a milestone today with the delivery of the 5,000th locomotive in the series.

The landmark locomotive was delivered to the Union Pacific Railroad under the road number 7964 and will be featured in a Denver Post Cheyenne Frontier Days event that is part of the railroad’s 150th anniversary.

The General Electric Co. has been building locomotives for most of the company’s 100 years in Lawrence Park. But the Evolution, introduced just seven years ago, ranks as the company’s fastest selling model ever.

The Evolution, designed to use 11 percent less fuel than earlier models, has been billed by the company as the world’s most environmentally friendly locomotive.

Lorenzo Simonelli, chief executive of GE Transportation, called the delivery of the 5,000 Evolution, “a historic milestone.”