The Irish & the Chinese.
The Irish and Chinese were the 2 main groups doing the manual labor.
The Irish, Chinese, and African Americans comprised the workforce on the Transcontinental Railroad.
Chinese and Irish
Chinese and Irish immigrants
ChineseApex
If speaking purely on ethnic groups responsible in building the American railroad system -- the answers are: German, Irish, and Chinese.
Caucasian and oriental were the two main ethnic groups. The labor force was made up Chinese and Irish immigrants, as well as veterans of the American Civil War. The veterans would have included African Americans and Hispanics. Source: Wikipedia, First Transcontinental Railroad.
The four labor groups that built the Transcontinental Railroad were the Canadian and British engineers and surveyors, manual labor crews made up of former slaves and emigrant Chinese, semi-skilled laborers made up from discharged Union and Confederate troops, and emigrant Irishmen. The supervisory crew was made up of whites, including some Irish.
A train route across the United States. It was the project of two railroad companies: the Union Pacific built from the east, and the Central Pacific built from the west. The two lines met in Utah. The Central Pacific laborers were predominantly Chinese, and the Union Pacific laborers predominantly Irish. Both groups often worked under harsh conditions.
Some of the religious groups that assisted in the organization of the Underground Railroad were the Quakers, various Methodist denominations, and the African Methodist Episcopal Church. These groups often provided safe houses, financial support, and guidance to freedom seekers.
It is difficult to answer this question without knowing whether the question refers to continents, groups of countries, regions within a country or within a smaller geographic unit.
These groups made loans and provided legal assistance