What is the company that built transcontinental railroad from California eastward?

The company that built the transcontinental railroad from California eastward was the Central Pacific Railroad. The Central Pacific Railroad was incorporated in 1861 and began construction of the western portion of the transcontinental railroad from Sacramento, California, in 1863. The company faced numerous challenges during construction, including the Sierra Nevada mountains and the lack of available labor due to the Civil War. Despite these challenges, the Central Pacific Railroad completed its portion of the transcontinental railroad in 1869 when it met with the Union Pacific Railroad at Promontory Summit, Utah. The completion of the transcontinental railroad significantly reduced travel time and costs between the East and West coasts of the United States and had a profound impact on the economic development of the country.