How do immigration enforcement needs correlate with undocumented immigrant population by state?
Executive summary
Undocumented-population estimates vary across reputable sources, but all show strong geographic concentration: a handful of states host a large share of the population, and enforcement “needs” — measured by detentions, removals, court dockets and local encounters — tend to follow those concentrations while also being reshaped by policy choices and capacity limits [1] [2] [3]. However, correlation is far from one-to-one because enforcement activity is driven as much by federal policy, detention and court capacity, and local state responses as by raw counts of undocumented residents [4] [5] [6].
1. The data landscape: contested totals and state maps
Researchers produce different national and state estimates — Migration Policy Institute, Center for Migration Studies, Pew, and others report figures ranging from roughly 11–14 million unauthorized immigrants in recent years — and each dataset uses distinct methods that affect state-level totals and shares [1] [7] [8] [9]. DHS’s Office of Homeland Security Statistics publishes tabulations of unauthorized residents by state and entry period that are commonly used to allocate enforcement attention, but variations across sources mean “how many” people live in each state is not a single settled fact [3].
2. Concentration matters: where populations and encounters cluster
Immigrants — including the unauthorized — are heavily concentrated: the share of immigrants in state populations ranges from about 2 percent in West Virginia to roughly 27 percent in California, and that geographic skew means enforcement workload is often concentrated in a small number of states and counties [2]. Migration Policy Institute and other state profiles show a handful of large states host the majority of unauthorized residents, and federal enforcement historically deploys more personnel, detention beds and court resources where caseloads are largest [1] [10].
3. Enforcement capacity and federal policy reshape needs and activity
Federal policy decisions and funding shifts can change enforcement “needs” independent of population: the Congressional Budget Office projected that new immigration enforcement funding would increase detention averages to about 50,000 immigrants held per day over 2026–2029 and add hundreds of thousands of court cases and removal orders, illustrating how congressional and administrative choices can expand enforcement workload irrespective of the underlying state population map [4]. Brookings and related analyses also emphasize that changes in enforcement posture — such as expanded fast-track deportation authorities or termination of parole programs — alter flows and therefore enforcement burdens [11].
4. Operational measures — detention, removals, courts — define practical needs
Practical enforcement needs are operational: detention bed inventories, ICE removal and arrest statistics, and immigration court backlogs dictate where additional agents, judges, or state cooperation are required; CBO estimated an increase of roughly 210,000 additional immigration court cases tied to increased hiring and enforcement, underlining the administrative component of enforcement demand [4]. DHS OHSS monthly and state tables are the backbone for allocating these operational resources because they break down encounters and residence by state [3].
5. Why population and enforcement do not perfectly correlate
Several factors break the simple population-to-enforcement link: shifts in border enforcement and parole programs change inflows and interior encounter patterns over short timescales, producing large local variation even as resident populations change slowly [6]. State laws and sanctuary policies shape cooperation with federal authorities and thus where enforcement is concentrated, and advocacy and policy groups lobby states to limit or expand data sharing and resource access — meaning politics and state law alter enforcement footprints beyond demographic signals [5].
6. Bottom line: correlated but mediated by policy, capacity, and politics
Undocumented-population concentrations by state are a primary predictor of where enforcement resources and activity will be needed, but the strength of that correlation is mediated by federal policy choices, detention and court capacity, shifting border flows, and state-level cooperation or resistance; authoritative projections and operational allocations therefore rely on both demographic estimates (MPI/CMS/Pew/DHS) and policy-driven capacity planning [1] [7] [8] [3] [4]. Reporting that treats population maps as a direct proxy for enforcement demand misses these institutional levers that often determine where and how intensively enforcement is actually carried out [4] [5].