How does documentation affect immigrants' rights in the United States?

Documentation is everything. Permanent resident aliens with valid green cards have most of the same rights and privileges as citizens, and naturalized citizens have all of them (except for running for President, for some reason). Permanent residents can work here permanently, use public schools, and apply for services such as Social Security and Medicaid. Naturalized citizens can do all these things as well as even vote and run for office.Undocumented immigrants, however, can do...

Documentation is everything. Permanent resident aliens with valid green cards have most of the same rights and privileges as citizens, and naturalized citizens have all of them (except for running for President, for some reason). Permanent residents can work here permanently, use public schools, and apply for services such as Social Security and Medicaid. Naturalized citizens can do all these things as well as even vote and run for office.

Undocumented immigrants, however, can do none of these things. In most states they are ineligible for all government services except for emergency services (though in some states they can use public schools). They can be arrested, detained, and deported, essentially whenever Immigration and Customs Enforcement wants to do so. While most undocumented immigrants try to find work, they cannot legally work for formal employers and so they usually end up working under the table for below minimum wage.

Knowing this, why would anyone not become documented? Because it's simply too difficult. The multiple layers of bureaucracy, high costs, and absurdly long delays (on the order of years or even decades) to obtain permanent residency or citizenship prevent millions of immigrants from obtaining citizenship even though they desperately would like to and should be eligible.