Non-U.S. citizens can be admitted to the U.S. on a permanent basis in three general categories: family reunification, employment sponsorship and humanitarian cases. The number of people granted lawful permanent residence (LPR) status each year
Employment-based immigration, another path to permanent settlement, is available to employees with a range of skill levels under four separate categories, most of which require that an applicant be sponsored by an employer. A fifth category provides for the admission of investors. Employment-based admissions are limited to 140,000 per year, plus any unused family preferences from the previous year, with a 7% annual cap per sending country. Finally, the Diversity Lottery awards LPR status to citizens of countries which have not sent more than 50,000 immigrants to the U.S. in the previous five years. Since 1999 the annual limit for admissions in this category has been 50,000. The names of eligible countries are published by the State Department before each year's lottery begins. In 2011, the per-country limit of diversity visas was 3,500.
In addition to these means of entry for permanent settlement, there is a wide variety of visa categories for the admission of temporary residents, or so-called "nonimmigrants [sic!]", all of which are subject to numerical limits. For example, 65,000 work visas for temporary highly-skilled workers (H-1B) are made available each year (plus an extra 20,000 for foreign graduates of U.S. universities), as are 66,000 work visas (H-2B) for seasonal workers or workers needed to fill temporary labor shortages in sectors such as construction, health care, landscaping, lumber, manufacturing, food service/processing and resort/hospitality services. According to DHS estimates there were 159 million nonimmigrant admissions in the U.S. in 2011. Of these, 87% were tourist and business travelers.
The number of people receiving LPR status each year has been increasing since the Second World War, quadrupling from an average of 250,000 persons per year in the 1950s to just over one million per year in the period from 2000 to 2011.
In 2011, a total of 1,062,040 people were awarded LPR status, 481,948 (45.4%) of whom were new arrivals, and 580,092 (54.6%) of whom had adjusted their status (i.e. were not new immigrants, but people who had applied for LPR status while living in the U.S. under a different permit). A total of 688,089 people (64.8%) acquired LPR status under family reunification provisions, 139,339 (13.1%) in the employment-based category, 50,103 (4.7%) in the Diversity Lottery, 168,460 (15.9%) as refugees and asylees, and the remainder via other categories. The top 3 countries of birth of new LPRs were Mexico (14%), China (8.2%), and India (6.5%).