Which railroad company was responsible for building from the middle of the united states westward? union pacific central pacific kansas nebraska california kansas 2. the central pacific railroad filled much of its need for labor by hiring immigrants. russian japanese irish chinese 3. the transcontinental railroad completed at omaha, nebraska santa fe, new mexico promontory point, utah sacramento, california?

Union Pacific was responsible for the building of the rail lines from Kansas westward. 
The Central pacific hired mostly Chinese immigrants to lay its lines. They also used their valuable knowledge of dynamite to help blast through the Rockies. 
The railroad lines met at promontory point, Utah. Most of the line had been laid by the Union Pacific, but the Central Pacific had a much harder time getting through the mountains.