[Excerpt] The Immigration and Nationality Act (INA) specifies a complex set of categories and numerical limits for admitting lawful permanent residents (LPRs) to the United States that includes economic priorities among the admission criteria. These priorities are addressed primarily through the employment-based immigration system, which consists of five preference categories. Each preference category has specific eligibility criteria; numerical limits; and, in some cases, distinct application processes. The INA allocates 140,000 visas annually for all five employment-based LPR categories, roughly 12% of the 1.1 million LPRs admitted in FY2017. The INA further limits each immigrant-sending country to an annual maximum of 7% of all employment-based LPR admissions, known as the per-country ceiling, or “cap.” Prospective employment-based immigrants follow two administrative processing trajectories depending on whether they apply from overseas as “new arrivals” seeking LPR status or from within the United States seeking to adjust to LPR status from a temporary status that they currently possess. While some prospective employment-based immigrants can self-petition, most require U.S. employers to petition on their behalf. In both cases, the Department of State (DOS) is responsible for allocating the correct number of employment-based immigrant “visa numbers” or slots, according to numerical limits and the per-country ceiling specified in the INA. This report reviews the employment-based immigration process by examining six pools of pending petitions and applications, representing prospective employment-based immigrants and any accompanying family members at different stages of the LPR process. While four of these pools represent administrative processing queues, two result from the INA’s numerical limitations on employment-based immigration and the per-country ceiling.