GE Transportation was considered the largest producer of diesel-electric locomotives in North America, and has been essential in producing locomotives since 1912. Following several partnerships in creating locomotives, it wasn't until 1956 and the release of their Universal Series for export, that they became a serious competitor. The U-Boats of North America, soon followed suit, a larger gauge and heavier than the initial universal series garnering domestic commercial success. Constructed from a U25B, the General Electric U25C ended up even longer; the first second generation diesel engine on six axles made its debut in 1963. Operating under the name Burlington Northern from 1970 through 1996, consisted of merging four prominent railroads after over 60 years of failed attempts to combine these companies that was continuously blocked by the Supreme Court; eventually they were finally able to form the Burlington Northern Railroad. During its years of operation, Burlinngton Northern acquired many other railroads and by the end of its reign in 1996, managed over 27,000 miles of track from Chicago Westward, including passengers, freight services and cleaner fuel options, connecting the country through their vast network of railways serving their customers as they innovated logistic operations along the way before becoming BNSF as it is known today.