What is a sanctuary city? And why Trump's presidential plan includes getting rid of them

One of the defining components of President-elect Donald Trump's campaign was the hardline (oftentimes xenophobic) stance he took on immigration.  One of the promises Trump made on the campaign trail was to end sanctuary cities after the murder of San Francisco woman Kate Steinle, allegedly by an undocumented immigrant. 

"We will end the sanctuary cities that have resulted in so many needless deaths," Trump said during a speech. "Cities that refuse to cooperate with federal authorities will not receive taxpayer dollars, and we will work with Congress to pass legislation to protect those jurisdictions that do assist federal authorities."

Republicans have always taken issue with sanctuary cities, voting on the Stop Sanctuary Policies and Protect Americans Act, which would've blocked federal funds from sanctuary cities, in 2015. The bill failed to pass.

What are sanctuary cities?

A sanctuary city is a city that shelters undocumented immigrants. According to apsanlaw.com, these cities "do not permit municipal funds or resources to be applied in furtherance of enforcement of federal immigration laws." In these cities, local and state government employees are often instructed not to inquire about one's immigration status and told not to report undocumented workers.

In some sanctuary cities, if an undocumented immigrant is caught committing a crime, say driving without a license, they will be ordered to serve jail time or pay fines, but will then be let go, according to the Washington Post.

Since there is no official designation for sanctuary cities, policies vary across the board.

Which U.S. cities are considered sanctuary cities?

According to the Washington Times, more than 340 U.S. cities are considered sanctuary cities. Some of the larger cities that have vowed to continue protecting undocumented immigrants include New York City, Los Angeles, Seattle, Philadelphia, San Francisco and Austin, according to Remezcla.

Why do U.S. cities choose to shelter immigrants?

For the most part, cities that shelter undocumented immigrants have diverse, liberal communities. Many of these cities recognize deportation as the "wrong punishment" for undocumented immigrants, thus constituting a breach of civil law. It is often said that sanctuary cities encourage undocumented immigrants to work with local authorities without fear of deportation so that law enforcement can identify and arrest real criminals. A CNN report shows that chiefs from the country's largest police departments and police groups, such as the International Association of Chiefs of Police, support sanctuary cities because they help officers and communities to combat crime.

Do undocumented immigrants really commit more crimes?

Despite Trump's anti-immigrant rhetoric, immigrants are less likely to be criminals than native-born Americans, according to a report by the American Immigration Council.  It states that as undocumented immigrant population reached 11.2 million between 1990 and 2013, FBI data showed that "violent crime rate declined 48%" and "property crime rate fell 41%" during the same period.  

States with large immigrant communities also show a disconnect between newcomers and crime. A 2008 report by the Public Policy Institute of California found that the incarceration rate for foreign-born adults "is 297 per 100,000 in the population, compared [with] 813 per 100,000 for U.S.-born adults."