The building of the transcontinental railroad provide many jobs especially for immigrants. Which two immigrant groups completed much of the work on the transcontinental railroad

Irish and Chinese

The Chinese and the Mexican-Americans were the bulk of workers who built the American transcontinental rairoad in the 19th century. The Chinese arrived in large numbers in the second half of the century escaping poverty and turmoil in China, and there were large Mexican populations living in the USA. Only agricultural work offered more employment to Mexicans than the railroad works.