Final answer:
The First Transcontinental Railroad began in Omaha, Nebraska, and ended in Sacramento, California, with its completion in 1869 marked by a golden spike at Promontory Point, Utah.
Step-by-step explanation:
The First Transcontinental Railroad was a monumental feat that transformed the United States by providing a coast-to-coast rail link for the first time. The construction started in Omaha, Nebraska, and extended westward, while simultaneously another railroad expanded eastward from Sacramento, California. The two lines were financed largely by the 1864 grant of federal lands to the Union Pacific and Central Pacific railroads. Both lines were completed in 1869, and a ceremonial golden spike was driven at Promontory Point, Utah, marking the union of the two railroads. Thus, the transcontinental railroad started in Omaha, Nebraska, and ended in Sacramento, California, with further connections to San Francisco and Oakland.