Select the factors that caused immigration limits to be enforced

Immigration reduction refers to a movement in the United States that advocates a reduction in the amount of immigration allowed into the country. Steps advocated for reducing the numbers of immigrants include advocating stronger action to prevent illegal entry and illigal immigration, and reductions in non-immigrant temporary work vistas. Some advocate a tightening of the requirements for legal immigration requirements to reduce total numbers, or move the proportions of legal immigrants away from those on family reunification programs to skills-based criteria. What separates it from others who want immigration reform is that reductionist see immigration- or one of its forms- as being a significant source of social, economic, and environmental problems, and wish to cut current immigration levels.Many immigration reformists support continued legal immigration, only opposing illegal immigration. Some immigration reductionist want legal immigration to be set at a percentage of current levels until fewer adverse effects are created by legal immigration.The related terminology "self-deportation" or "to self-deport" refers to the viewpoint that social policy that illegal immigration to the U.S. can be reduced by causing residents to leave the U.S. on their own, thus creating a reduction.