A demand for labor and a supply of immigrants in search of economic opportunity coincided in the Antebellum period. As the manufacturing sector in the Northeast expanded rapidly, managers sought large pools of unskilled or semi-skilled labor. Meanwhile, in Ireland, beginning in 1845, a disastrous blight fell on the staple crop, potatoes. This created a major famine that forced millions of Irish people into starvation. From 1847 to 1854, over 1.25 million Irish people moved to the United States to escape the famine, some as a result of American labor recruiters in Ireland.

The Irish immigrants of the 1840s and 1850s were largely poor and unskilled, unlike the more socio-economically diverse Irish immigrants of previous decades. Swindlers took advantage of immigrants coming into port cities. In 1855, however, New York City, the major port of entry for immigrants, established facilities in lower Manhattan which registered and processed immigrants, and provided them with information on finding their relatives and traveling to final destinations in the United States. This helped reduce the amount of trickery to which immigrants were subjected.

Many of these new immigrants, especially the women, worked in factories and as domestics in the homes of the wealthy. While wages were low, the opportunities and pay were greater in the United States than in Europe. Others, largely men, worked in mines or mining towns. Life in the mining towns was full of hardships. Working in a mine was a major health hazard, and mine owners generally did not take adequate health precautions. Wages were low for long days of hard labor. Laborers and their families were required to live in company towns and purchase food and other items in company stores, which took shameful advantage of the unfortunately powerless immigrants. Fear of losing their jobs and the autocratic power of managers and owners prevented or squashed any attempts to protest the unfair working and living conditions.

Although a large portion of antebellum immigrants were Irish, there were also immigrants from other locations. German immigrants were another major group. Political revolts and revolution attempts in the 1840s across Europe, but especially in German-speaking areas (Germany, Austro-Hungarian Empire, etc.) caused many to flee to the United States for asylum or to escape the turmoil in the continent. Unlike Irish immigrants of the same period, however, German-speaking immigrants came from different social and economic classes, and many were skilled laborers or professionals. This made it was somewhat more difficult for native-born Americans to stereotype Germans than Irish, although ethnic stereotypes did exist. In addition, the larger number of Irish immigrants made native-born Americans feel more economically threatened by them than by German immigrants. Thus, the German antebellum immigrants generally assimilated into the United States more easily than the Irish. It was not until the Civil War, in which many Irish Americans served prominently, that the new Irish immigrants were able to achieve a sense of belonging.

The other major immigrant group introduced to the American tapestry in the antebellum period was the Chinese immigrant of the West. In the late 1840s, Chinese immigrants began arriving in the United States in significant numbers. By the early 1880s, about 250,000 Chinese and Chinese Americans lived in the United States, most of whom were located in California or other western territories and states. For the first few years, Chinese immigrants, mostly men, were the objects of curiosity, but relatively little social attack. Few knew English, and most worked for one of the Six Companies, which were Chinese organizations in the United States that governed the actions of Chinese immigrants. These companies took the place of village governments and patriarchal associations, and had their own laws, independent of American laws. Anyone disobeying the rules was quickly punished, regardless of relevant American laws. Living in fear, many Chinese immigrants were completely dependent on these companies, and interacted little with native-born Americans.

As the California Gold Rush of the late 1840s and 1850s brought more people to the state, Chinese immigrants found their attempts to pan for gold restricted by the racial prejudice of some of their fellow fortune-hunters. The more numerous and visible the Chinese were, the more they became the subjects of discrimination and ridicule. A large number worked in mines or on the construction of railroads, although relatively little mining and railroad construction occurred in the West until after the Civil War. Many Chinese immigrants and Chinese Americans had to turn to jobs that white men did not want to do themselves, such as making clothing, washing laundry or cooking for others. Nevertheless, through hard work and careful financial planning, many Chinese immigrants and Chinese Americans were able to make their businesses successful. By 1860, the Chinese were responsible for almost all the manufacturing of shoes, shirts, underwear, cigars and tin products in California. Many others owned their own laundries, restaurants and hotels, catering to the many single men living in the West.

When the West experienced economic difficulties, Chinese Americans were among the first to be attacked, verbally and physically. In addition, territories and states passed discriminatory laws. For example, Chinese people were the only group which had to pay an annual $20 tax required of foreign miners in California. White westerners began creating stereotypes of Chinese Americans, depicting them as belonging to a retrogressive and inferior race. Popular culture readily adopted the cruel stereotypes and ridiculed Chinese Americans in pictures, verbal expressions and myths. Chinese Americans were soon categorized with Native Americans and African Americans, as inferior peoples. While they were not strictly enslaved, they were not strictly free. This war was marked by a series of bloodless skirmishes on the border between Maine and Canada. This border had never been clearly defined and thus was disputed by both sides. President Van Buren sent General Winfield Scott to negotiate a deal. Scott was able to arrange a truce.