How Many Illegal Immigrants Are in the US?

The number of illegal immigrants living in the United States is a major topic in discussions about immigration policy, border security, employment, and the national economy. Millions of people live in the country without full legal immigration status, making unauthorized immigration an important issue for federal and state governments.

According to estimates published by the Migration Policy Institute (MPI) in July 2026, approximately 15.8 million unauthorized immigrants lived in the United States in mid-2024. This represents a substantial increase compared with previous decades.

However, there is no exact official count of illegal immigrants in the United States. Immigration authorities and research organizations use different data sources and statistical methods to estimate the population.

Understanding these numbers requires looking beyond border crossings and examining the different ways people enter, remain in, and eventually leave the country.

What Is the Estimated Number of Illegal Immigrants in the US?

The estimated number depends on the research organization and the methodology used.

Here are some important estimates:

• 2023: Pew Research Center estimated approximately 14 million unauthorized immigrants, representing about 4.1% of the total U.S. population.

• Mid-2024: The Migration Policy Institute estimated approximately 15.8 million unauthorized immigrants.

• 2024: A Congressional Research Service report published in September 2026 cited estimates ranging from 14.6 million to 15.8 million.

These figures indicate that the unauthorized immigrant population increased significantly between 2019 and 2024.

It is important to remember that these are estimates rather than exact government counts. Different organizations may use different definitions of unauthorized immigration, which can produce different results.

Why Is It Difficult to Count Illegal Immigrants in the United States?

One reason it is difficult to determine how many illegal immigrants are in the US is that the U.S. Census Bureau does not directly ask every respondent whether they are living in the country legally.

Instead, researchers combine information from population surveys, immigration records, visa data, and other government statistics.

Several factors make an accurate count challenging.

1. Undocumented border crossings

Some individuals enter the United States without going through official immigration inspection. Not everyone who enters this way is identified or recorded.

2. Visa overstays

Not all unauthorized immigrants cross the U.S.-Mexico border illegally. Some originally enter the country legally with tourist, student, or other temporary visas but remain after their authorized period expires.

3. Changing immigration status

Some immigrants may initially lack permanent legal status but later receive asylum, temporary protection, or other immigration benefits. Their legal circumstances can change over time.

4. Voluntary departures and deportations

People may leave the United States voluntarily, receive legal immigration status, or be deported. These changes make it difficult to maintain an exact population figure.

For these reasons, immigration researchers generally rely on statistical estimates rather than a single official count.

Where Do Most Illegal Immigrants in the US Come From?

Unauthorized immigrants living in the United States come from many different countries. Although Mexico remains the largest country of origin, immigration patterns have become more diverse over the years.

According to MPI's mid-2024 estimates, the largest groups included:

Mexico accounts for the largest share of the unauthorized immigrant population. However, migration from Central and South America has increased considerably.

Economic difficulties, political instability, violence, family reunification, and the search for better employment opportunities are among the factors influencing migration decisions.

Which US States Have the Most Illegal Immigrants?

Unauthorized immigrants are not evenly distributed across the United States. Some states have significantly larger populations because of employment opportunities, established immigrant communities, geographic location, and family connections.

States commonly associated with large unauthorized immigrant populations include:

California

California has historically been one of the leading destinations for immigrants without legal status. Its large agricultural, construction, hospitality, and service industries provide employment opportunities.

Texas

Texas has a large immigrant population due partly to its location along the U.S.-Mexico border. Major metropolitan areas such as Houston, Dallas, and San Antonio also attract immigrants seeking work and established communities.

Florida

Florida has experienced substantial immigration from Latin America and the Caribbean. Agriculture, tourism, construction, and hospitality are important employment sectors.

New York

New York attracts immigrants from many regions of the world. Its large service economy, international communities, and established immigrant networks make it a major destination.

New Jersey

New Jersey has a significant immigrant population, particularly in metropolitan areas connected to New York City and Philadelphia.

Other states with substantial unauthorized immigrant populations include Illinois, Georgia, North Carolina, and Arizona.

The distribution of unauthorized immigrants is influenced by economic conditions, housing availability, family connections, and state-level immigration policies.

How Do Illegal Immigrants Enter the United States?

There are several ways people become unauthorized immigrants in the United States.

Crossing the border without authorization

Some individuals enter the country without receiving permission from U.S. immigration authorities. The southern border with Mexico has historically been a major route for unauthorized migration.

Overstaying a visa

A person may enter the United States legally with a tourist, student, or business visa but remain after the authorized period of stay expires.

Visa overstays are an important part of the unauthorized immigrant population and demonstrate why border crossing statistics alone cannot explain the total number of people living in the country without full legal status.

Temporary immigration programs

Some individuals enter or remain in the United States through temporary humanitarian programs, parole arrangements, or other forms of protection. Depending on the research definition, people in these categories may be included in unauthorized immigrant estimates even when they have permission to remain temporarily.

This distinction is important because not everyone included in an unauthorized immigrant estimate entered the country illegally.

What Jobs Do Illegal Immigrants Have in the United States?

Unauthorized immigrants participate in several important sectors of the American economy.

According to Pew Research Center, approximately 9.7 million unauthorized immigrants were part of the U.S. workforce in 2023, accounting for about 5.6% of all workers.

Common employment sectors include:

• Construction: Residential construction, roofing, landscaping, renovation, and other building services.

• Agriculture: Crop production, harvesting, food processing, and agricultural labor.

• Hospitality: Restaurants, hotels, food services, and tourism-related businesses.

• Manufacturing: Production, packaging, warehousing, and factory operations.

• Cleaning and maintenance: Commercial cleaning, residential services, and property maintenance.

Their participation in these industries has economic consequences. Businesses may depend on immigrant labor to fill certain positions, while workers without legal authorization can face significant challenges involving wages, workplace protections, and employment security.

What Is the Economic Impact of Illegal Immigration?

The economic impact of unauthorized immigration is complex and continues to generate debate among policymakers, economists, and business owners.

On one hand, unauthorized immigrants contribute labor, consumer spending, and economic activity. They rent or purchase housing, buy groceries, use transportation services, and support businesses in local communities.

Some industries also rely heavily on immigrant workers to maintain production and control labor costs.

On the other hand, unauthorized immigration creates policy challenges involving public resources, immigration enforcement, labor regulations, and access to certain government services.

The fiscal impact can differ significantly depending on the state, local tax system, age distribution, employment levels, and eligibility rules for public benefits.

It is therefore difficult to describe the overall economic consequences with a single number.

Are Illegal Immigrants Increasing or Decreasing in the US?

The unauthorized immigrant population has experienced several periods of growth and decline.

Between 2007 and 2019, the population generally declined or remained relatively stable, according to historical estimates.

However, the trend changed after 2019. Pew Research Center estimated that the population increased from 10.5 million in 2021 to 14 million in 2023.

MPI subsequently estimated that the number reached approximately 15.8 million by mid-2024.

More recent immigration trends have also been affected by changes in border enforcement, humanitarian immigration programs, deportation policies, and voluntary departures.

Because population estimates rely on surveys and other statistical information, it is important to distinguish between confirmed historical estimates and preliminary indications of more recent changes.

What Is the Difference Between Illegal Immigrants and Undocumented Immigrants?

The terms illegal immigrants, undocumented immigrants, and unauthorized immigrants are often used interchangeably in everyday discussions. However, there are some important distinctions.

An illegal immigrant generally refers to someone who enters or remains in a country without authorization.

An undocumented immigrant usually refers to someone who does not have valid immigration documentation or whose immigration status cannot be properly documented.

Unauthorized immigrant is a broader research term commonly used by organizations such as Pew Research Center and the Migration Policy Institute.

It can include people who entered without inspection, overstayed visas, or have temporary and uncertain immigration protections.

The terminology matters because different definitions can affect how researchers calculate the total immigrant population.

What Could Happen to Illegal Immigration in the United States?

The future size of the unauthorized immigrant population will depend on several factors.

Changes in immigration enforcement

Increased border security, deportations, and immigration enforcement could reduce the number of people living in the country without authorization.

Changes in immigration laws

New legislation or executive policies may affect asylum procedures, temporary protections, employment authorization, and pathways to legal residency.

Economic conditions

The availability of jobs, wages, housing costs, and economic opportunities in the United States can influence migration decisions.

Conditions in other countries

Political instability, violence, unemployment, and economic crises in countries of origin may continue to encourage people to migrate.

These factors interact with one another, making it difficult to predict the exact number of unauthorized immigrants in the coming years.

Conclusion

So, how many illegal immigrants are in the US?

The latest major estimate from the Migration Policy Institute places the unauthorized immigrant population at approximately 15.8 million in mid-2024. Other research organizations have produced estimates within a similar range, although their methodologies and definitions differ.

Unauthorized immigration remains an important issue affecting American politics, employment, housing, border security, and the national economy.

For anyone researching U.S. immigration trends, it is essential to understand not only the total population but also where immigrants come from, how they enter the country, and how immigration policies influence population changes over time.

As new government data and research become available, estimates of the unauthorized immigrant population will continue to evolve.