Understanding the US Immigration System
The United States immigration system is governed by the Immigration and Nationality Act of 1965, as amended, along with numerous executive branch regulations and a large body of case law. The system distinguishes between lawful permanent residents (green card holders), visa holders (temporary status of various kinds), undocumented immigrants, and individuals in various forms of humanitarian status.
Approximately 45 million foreign-born individuals live in the United States — about 14% of the population. Of these, roughly 12 to 14 million are estimated to be undocumented. The undocumented population has actually declined from its peak of about 12.2 million in 2007, partly due to enforcement and partly due to changing migration patterns.
Immigration policy is both federal and deeply political. The federal government has exclusive authority to set immigration rules under the Constitution's plenary power doctrine. States cannot create their own immigration categories or grant immigration status. However, states and localities have significant discretion over whether to cooperate with federal immigration enforcement — the source of ongoing conflict over "sanctuary city" policies.
Legal Immigration Pathways
Legal immigration to the United States occurs through several main categories. Family-based immigration allows US citizens and permanent residents to sponsor close relatives for green cards. Employment-based immigration allows employers to sponsor skilled workers and certain other categories. The diversity visa lottery provides 50,000 green cards annually to nationals of countries with historically low immigration rates to the US. Humanitarian categories include refugees, asylees, and individuals with special immigrant juvenile status.
Backlogs are a defining feature of the legal immigration system. Per-country annual caps mean that applicants from high-immigration countries face waits measured in decades for certain categories. An employment-based applicant from India in certain visa categories may wait more than 50 years at current processing rates — a policy outcome that many immigration lawyers and economists argue undermines the system's utility.
The Border: Numbers and Context
US Customs and Border Protection records "encounters" at the Southwest border — a metric that includes both unique individuals apprehended and repeat crossers. In fiscal year 2022 and 2023, annual encounters exceeded 2 million, reaching levels not seen in prior decades. The increase reflects factors including economic conditions in sending countries, violence, US labor market demand, and the administrative backlog in asylum processing.
Migrant nationality has shifted significantly. The traditional pattern of Mexican economic migration has given way to a more diverse flow from Central America, Venezuela, Ecuador, Cuba, and Haiti, with growing numbers from China and other countries. These demographic shifts affect both legal claims (Central American gang violence can support asylum claims; economic migration generally does not) and logistical processing.
Why Congress Has Not Acted
Comprehensive immigration reform has been attempted and failed repeatedly — the Gang of Eight bill in 2013 passed the Senate but died in the House, and numerous other efforts have stalled. The fundamental problem is that any comprehensive deal requires both enforcement measures that conservatives demand and legal status provisions for long-term residents that progressives require. Each side's base is more motivated by opposing the other's priorities than by enacting their own.
As a result, immigration policy has increasingly been made through executive action — subject to reversal by successive administrations and challenge in federal courts — rather than durable congressional legislation. This has created a policy environment of high uncertainty for immigrants, employers, and state and local governments trying to plan around federal policy.
Frequently Asked Questions
What is DACA and what is its current status?
DACA protects immigrants who arrived as children from deportation and provides work authorization. Approximately 580,000 people hold DACA status. The program continues to face federal court challenges as of early 2026.
What is the difference between asylum seekers and undocumented immigrants?
Asylum seekers formally request protection upon reaching the US based on persecution in their home country. They are in a legal process. Undocumented immigrants entered without authorization or overstayed visas. These are distinct legal categories with different rights and processes.
How many legal immigrants does the US admit each year?
Roughly 1 million to 1.1 million lawful permanent residents annually. Family-based immigration is the largest category, followed by employment-based, diversity visa lottery, and humanitarian categories.
What executive actions has the current administration taken on immigration?
Expanded border enforcement, increased deportation operations, modified asylum processing rules, and changes to expedited removal authority. Many of these actions have faced federal court challenges.
Why hasn't Congress passed comprehensive immigration reform?
Democrats prioritize legal status pathways; Republicans prioritize enforcement. Comprehensive deals require accepting both — politically unacceptable to each party's base. This has driven immigration policy into executive action rather than durable legislation.