The youngest and largest merger of any Cabinet department — created by folding 22 separate agencies into one.
DHS coordinates border security, immigration enforcement, disaster response, transportation security, and cybersecurity. Most people encounter it through TSA at the airport or immigration processes, without realizing both sit under the same department created after 9/11.
DHS was created with the singular goal of ensuring a safer, more secure America.
Department of Homeland Security mission statement
What It Does
DHS was created in 2002 in response to the September 11 attacks, merging 22 existing federal agencies into one department — the largest government reorganization since the Department of Defense was created in 1947. That merger explains why DHS’s components (TSA, ICE, CBP, FEMA, Secret Service, Coast Guard) can feel like they have little in common: they were separate agencies with distinct missions before 2002.
Secures borders and airports
CBP and TSA handle border security, customs, and transportation security screening.
Enforces immigration law
ICE and USCIS handle immigration enforcement and legal immigration processing.
Responds to disasters
FEMA coordinates federal disaster response and recovery assistance.
Protects cybersecurity
CISA coordinates cybersecurity defense for federal networks and critical infrastructure.
How It Fits Into Government
22 agencies folded into one in 2002
The Homeland Security Act of 2002 merged agencies including the Coast Guard, Secret Service, Customs Service, and the old Immigration and Naturalization Service into a single new department — each component kept much of its own distinct mission and culture even after the merger. Congress writes the statutes governing DHS’s many functions and funds its budget, one of the largest of any Cabinet department.
Major Components
TSA
Transportation Security Administration, airport and transit security screening.
- Airport screening
- TSA PreCheck
FEMA
Federal Emergency Management Agency, disaster response and recovery.
- Disaster declarations
- Recovery assistance
CBP and ICE
Customs and Border Protection, and Immigration and Customs Enforcement.
- Border security
- Immigration enforcement
How It Is Checked
Congress
Writes DHS’s founding and component statutes, and funds the department’s budget through annual appropriations.
Courts
Federal courts review immigration decisions, detention practices, and DHS rulemaking.
Public process
Immigration and security rules generally go through notice-and-comment before final adoption.
Inspector General
The DHS OIG audits programs and investigates misconduct across its many components.
Public Services Visitors May Need
Check an immigration case statusUSCIS case tracking tools.→
Find disaster assistanceFEMA relief programs after a declared disaster.→
Report a cybersecurity incidentCISA’s incident reporting channels.→
DHS’s components didn’t all start out related
A common misconception is that DHS was built from scratch as one unified agency. It was actually assembled from 22 previously separate agencies with genuinely different histories and missions — the Coast Guard traces to 1790, while TSA was brand new in 2001. That’s why a DHS component can feel oddly specific or narrow: it likely was, as an independent agency, before the 2002 merger folded it in.
