A tong (Chinese: 堂; Jyutping: tong4; Cantonese Yale: tong; literally: "hall"). is a type of organization found among Chinese immigrants living in the United States and Canada. In Chinese, the word tong means "hall" or "gathering place". These organizations are described as secret societies or sworn brotherhoods and are often tied to criminal activity. In the 1990s, in most American Chinatowns, clearly marked tong halls could easily be found, many of which have had affiliations with Chinese crime gangs.
Today tongs are, for the most part, members of the Chinese Consolidated Benevolent Associations, which are pro-Kuomintang traditional groups. These associations provide essential services for Chinatown communities such as immigrant counseling, Chinese schools, and English classes for adults. Tongs follow the pattern of secret societies common to southern China and many are connected to a secret society called the Tiandihui, which follows this pattern. Other groups worldwide that follow this pattern and are connected with the Tiandihui are known as hui, Hongmen, and triads.
Tongs first appeared in China in 1644 when the Ming dynasty was overthrown by the Qing dynasty. One of the first tongs was established by the secret society Zhigongtang (Chee Kung Tong), which aimed to restore the power of the Ming dynasty by removing the new Manchu rulers of the Qing dynasty. These Zhigongtang tongs were located in the province of Guangdong, which was home to many of the first Chinese migrants heading to America—some of whom would take with them the notion of a tong as an organization to set up there.
Prior to the 1840s, few Chinese emigrated to the United States or Canada. Large numbers had left China, particularly Fujian and Canton, since the seventeenth century in order to seek their fortune in southeast Asia and Taiwan. They formed a trader and merchant class in many societies: historic Philippines, Indonesia and Malayasia, for instance.
After settling in San Francisco and other California cities, Chinese workers faced hostility from their American peers who felt threatened by their being willing to work for lower wages. As labor unions and angered workers became more aggressive, many Chinese felt pressure to leave and go east, where they heard life would be less dangerous. As a result, many Chinese immigrants moved to cities such as New York, Philadelphia, and Boston. Today these cities still have ethnic Chinese communities large enough to have developed Chinatowns. They have also been joined by new immigrants of the late 20th and early 21st centuries. 
Many Chinese soon organized voluntary associations for support and protection. These focused around their originating district in China, family name, native dialect in the case of Hakka speakers, or sworn brotherhoods. The tongs were providing services for immigrants such as employment and housing opportunities. They also helped resolve individual and group disputes within the community. As Kolin Chin has asserted, many of these volunteer societies did not have the financial ability to fund community events or look after their members, and those that did tended to focus inward and provide help only to their own members. As a result, many tongs with little or no hereditary financial value had to either disband or operate activities such as gambling houses. This transformed them from benevolent associations to providers of illegal services. The term tong became associated with the secret brotherhoods that were in Chinatown, and they were often battling with other associations in that area. Tongs are usually composed of young men, some of which with criminal backgrounds, or outcasts who had been expelled from their associations. Notably, many of the traditional tong activities, such as gambling, were legal in China, but not in North America. The early Chinese populations in the United States and Canada were overwhelmingly male, a situation that worsened when sex-restrictive immigration laws were passed in 1882 in the USA and 1923 in Canada, respectively. (see Chinese Exclusion Act and Chinese Immigration Act, 1923) For this reason tongs participated heavily in importing women from China both for marriage and to serve as prostitutes. Many of these women did not come to America by choice, and some were deceived and forced into prostitution by procurers. Tongs associated with importing women to America fought over territories and profits. A large percentage of the "tong wars"—disputes between the rapidly growing and powerful tongs—of the 19th and early 20th centuries were often based on control of these women.  In the early years the tongs employed "hatchet men" or boo how doy as hired killers to fight the street battles that ensued over turf, business, and women.
San Francisco was the home of the first tong in the United States; it formed in reaction to the hostility that Chinese immigrants faced from American workers upon their arrival to America. During the plague outbreak in Chinatown of San Francisco in the 1900s, the Chinese Six Companies decided to suggest the vaccination plan to their members and the tongs. Doubting the effectiveness of vaccinations, the Chinese residents in Chinatown refused inoculations to avoid risks. Several of the tongs threatened to harm anyone who would get the vaccination and the Chinese leaderships.
Tongs in North America showed many similarities to Triad of Hong Kong and British-controlled southeast Asia. These included similar initiation ceremonies and paying respect to the same deities. This is because both are similar organizations that follow the patterns of southern Chinese secret societies and sworn brotherhoods. The Triad societies were underground organizations in British controlled areas that also existed for self-help of members, but spoke of the overthrow of the Qing dynasty. Ko-lin Chin outlined that most tongs have similar organization and have a headquarters where one can find a president, a vice-president, a secretary, a treasurer, an auditor, and several elders and public relations administrators. Today their main aims are to care for their members and their respective communities.