The majority of immigrants in the United States have had to face many dangers in their journey to reach the United States. This is especially true for many who may have entered the country illegally. Sometimes, illegal immigrants make various attempts to live in the United States, often attempting to cross the U.S.-Mexico border on several occasions. Even if illegal immigrants are caught at the border, many do not give up easily. Other times individuals residing in the United States illegally may have to go back to their native country for family reasons. Upon their return to the United States, they risk detection and possible deportation, even if they lived in the United States for many years.

Upon arriving to the United States, illegal immigrants sometimes find themselves in a “foreign” world since they may only be fluent in their homeland’s primary language. America has a higher standard of living than most countries, so immigrants may experience “culture shock.” They may be aware of some American traditions but not all of them. However, certain cities across the U.S. have reputations for being more immigrant-friendly. "Immigrant friendly" cities tend to have high immigrant populations in which the language of the individual's native country is commonly spoken. The transition to a new life in the U.S. is also usually eased by family and/or friends already in the United States. If one has family and friends in their new country, they may have higher chances of finding a job. Oftentimes, individuals immigrate to countries with a strong economy, so that they can achieve a higher standard of living than in their native country. Illegal immigrants also tend to reside in places where other immigrants are because it makes for a more friendly environment. Large immigrant communities often carry foods and products from back home. In addition, they may be less likely to face prejudice practices as many others can strongly relate to them and their humble beginnings.

Many cities that are considered immigrant-friendly are often referred to as "sanctuary cities." United States policy does not exactly offer a welcome mat for illegal immigrants, but sanctuary cities may have local policies that make life easier for immigrants. The reputations of sanctuary cities is often spread throughout the country. This can happen through word-of-mouth and through media coverage. In sanctuary cities there tends to be more support for illegal immigrants around the community. Some examples may include immigrant activists and church groups. However, there are also some community members who greatly disapprove of illegal immigrants and are vocal about it. Some American cities that have been classified as “sanctuary cities” include: San Diego, Los Angeles, San Francisco, Miami, Chicago, Seattle, Houston, Phoenix, Austin, Dallas, Washington D.C., Detroit, Salt Lake City, Minneapolis, Baltimore, Portland (both Maine and Oregon), Denver, New York City, Chicago and the whole state of New Jersey. Some cities disagree that they fall under this category and claim to be strict when it comes to immigration law enforcement. Cities can have formal or informal sanctuary policies. Formality is attained when the local government approves regulations in writing, such as an ordinance, order, resolution or policy. An informal sanctuary policy is not on paper but is a well-known discourse throughout the city and with city officials such as law enforcement. Unlike a formal sanctuary policy, there is no public record of informal sanctuary policy.

In 1996 a federal law called the Illegal Immigration Reform and Immigrant Responsibility Act was passed. It required that governments at the local level work together with Immigration and Customs Enforcement (ICE). Throughout the nation there has been an increased level of cooperation among different branches of government and government agencies, especially after the terrorist attacks of 9/11. However, cooperation varies from location to location. There is added pressure for local and state governments to comply with federal regulations governing immigration policy, especially with funding at stake. Cities have limited budgets to provide services to their communities, and populations remain on the increase. Sometimes immigrants become scapegoats for limited budges, and discrimination against them becomes more widespread. As a result, some cities have tried to pass legislation to discourage illegal immigrants from residing in certain areas. However, certain regulations have been declared unconstitutional in the court system. Other cities have taken a different approach to avoid the possibility of discriminatory practices. It is a measure that prevents not only discrimination against illegal immigrants but also against U.S. citizens and permanent residents. Congress continues to struggle in finding an effective way to deal with immigration and introduce immigration reform. Sometimes this struggle is taken on by local governments. The result is that some cities end up being classified as sanctuary cities. However, even cities that are considered “sanctuary cities” are not exactly a safe haven for illegal immigrants.