According to Iris Chang what economic social and political forces led the United States to build the trans continental railroad

Economic: moving natural resources from West to East.

Political: expanding the democratic way of life.

Social: the population was expanding and many wanted to go to California to look for gold.

Explanation:

Iris Chang wrote a book in which she wrote of the history of the Central Pacific Railroad, although some writers consider she went forward with the myth, as fact. The transcontinental railroad was primarily designed to move natural resources from west to east in the United States, and there was no reliable transportation to cross the continent.

According to Chang, U. S. population was willing to move to the West, as gold was discovered in California, and the hard work the Chinese accomplished this dream, as Chinese workers were preferred over many other workers because they were more productive. Chang states that Chinese employees took the risks although the non-caring attitude of the white bosses towards their Chinese employees.