At the start of the Spring semester, I have my students write a research paper on the experience of one or four groups during the 19th century in America: women, soldiers, African-Americans, or immigrants. Much of the focus on immigration during that time is on European immigration, but I like to remind my students that here in California, other groups were immigrating during that same time. I find that most of my students are less familiar with the migratory experiences of people from Asia versus Europe or the Americas.
A great background resource connected to the Chinese experience and their role in building the transcontinental railroad can be found at: https://www.uscitizenship.info/Chinese-immigration-and-the-Transcontinental-railroad/
This website is a great starting point for students. It uses student friendly language while still offering a comprehensive account of Chinese immigrants and their role in the building of the railroad.
It also offers great links that include a time of their immigration, primary documents, and photographs of the period.