Most illegal immigrants in the USA are people who overstay their visa. The USA does NOT make any effort to find people who overstay their visa.
HOWEVER, living in the USA without legal documentation is VERY difficult, even in a so-called sanctuary city. That just means the local government has made an official statement that they are NOT going to seek out illegal immigrants. They do that because illegal immigrants are often targets for crime, and the states don’t want anyone to be afraid to call the police. Immigration is a federal issue, but most crimes are state and local issues.
Wherever you live, you cannot legally work. Employers who hire illegal immigrants generally treat them very badly. They know that the illegal immigrant does not dare complain if the working conditions are unsafe, or the employer cheats them on their pay. Such an employer is dishonest, and often it is the employer who reports an illegal immigrant so they can blame the immigrant for their crimes. That is just one reason most states DON’T want to be part of any immigration enforcement.
Illegal immigrants can’t open a bank account, can’t get credit, can’t buy a house, can’t legally drive, can’t get insurance, can’t get on a airplane, can’t get any government services or benefits.
If an illegal immigrant is accused of a crime – innocent or not – they will be arrested and deported.
If an illegal immigrant gets sick, they can’t go to a hospital because they risk discovery and would then be arrested and deported.
Once someone overstays their visa, they have little hope over ever getting legal status in the USA. The rest of their life will be spent struggling to find food and shelter and stay healthy in slum areas.
It only makes sense for people who’s life in their home country is even worse.
For many, it is.
But many come to the USA thinking the “land of opportunity” will make it possible for them to live happy, productive lives. They don’t understand that it is true ONLY for legal immigrants.