Underserved populations are groups of people who face systematic barriers to health care, healthy environments, and the social conditions that keep people well. The term covers a broad range of communities, from rural residents who lost their local hospital to racial and ethnic minorities shouldering a disproportionate burden of pollution, from older adults who cannot get transportation to a clinic to children whose families cannot afford insurance. What ties these groups together is not a single shared trait but a pattern: the resources that protect health are distributed unevenly across society, and certain people end up on the short end repeatedly.
Who Counts as Underserved
There is no single checklist. The label applies to any community where access to care, exposure to health risks, or quality of available services falls measurably below what other groups receive. That includes people facing poverty, racial and ethnic minorities, immigrants with limited English proficiency, residents of remote or rural areas, LGBTQ+ individuals, people with disabilities, incarcerated or formerly incarcerated individuals, Indigenous communities, and older adults living alone or in under-resourced settings. These categories overlap constantly. A low-income Black woman in a rural county may face racial discrimination, geographic isolation, insurance gaps, and environmental hazards all at once.
Research on marginalization frames these barriers through what public health calls social determinants of health: the conditions in which people are born, grow, work, and age. Scientific advances in health care have been unevenly distributed across social strata, and disease burden follows the same uneven pattern, with marginalized groups carrying the highest risk of poor health outcomes.1PubMed Central. Marginalization: Conceptualizing patient vulnerabilities in the framework of social determinants of health-An integrative review As patients move through the health care system, barriers pile up at each step, and communities already facing disadvantage are the ones most likely to fall through the gaps in screening, diagnosis, and treatment.2PubMed Central. Social Determinants of Health Framework to Identify and Reduce Barriers to Imaging in Marginalized Communities
When the Nearest Hospital Disappears
Geography is one of the most concrete barriers to care. Rural communities across the United States have watched their hospitals close at an accelerating pace over the past two decades, and the consequences show up in measurable delays. A study of rural hospital closures found that average emergency transport times increased by about two and a half minutes and total activation time (from the initial 911 call to hospital arrival) climbed by roughly seven minutes.3PubMed Central. The effect of rural hospital closures on emergency medical service response and transport times Seven minutes may sound modest in everyday life, but for a stroke or a heart attack, that gap can mean the difference between recovery and permanent damage.
The ripple effects go beyond emergencies. Research on closures found that admissions for conditions that could have been managed in primary care spiked right before and for nearly two years after a hospital shut down, suggesting that communities losing a hospital also lose the broader web of primary care and outpatient services that kept people out of the hospital in the first place.4PubMed. Impact of rural hospital closures on hospitalizations and associated outcomes for ambulatory and emergency care sensitive conditions Where primary care is already scarce, people turn to emergency departments for conditions that do not require one. A national study found that for every ten additional medically underserved individuals per hundred people in a community, annual emergency department visits rose by more than three per hundred people, even after adjusting for demographics and insurance coverage.5PubMed. National study of the relation of primary care shortages to emergency department utilization
The Environment You Live In
Underserved populations do not just face barriers to care. They are often surrounded by conditions that make them sicker in the first place. Food deserts, neighborhoods with little or no access to affordable fresh food, are one well-documented example. Research on pregnant women found that living in a more severe food desert was linked to higher body fat and poorer blood sugar regulation during pregnancy, even after accounting for income.6Scientific Reports. The association between food desert severity, socioeconomic status, and metabolic state during pregnancy in a prospective longitudinal cohort On a population scale, counties with the worst food desert conditions had roughly double the mortality rate from metabolic liver disease compared to counties with the best food access.7PubMed. Food Swamps and Food Deserts Impact on Metabolic Dysfunction-Associated Steatotic Liver Disease Mortality in US Counties
Air pollution follows a similar pattern. Globally, an estimated 716 million people living in extreme poverty are exposed to unsafe levels of fine particulate matter, with the majority in Sub-Saharan Africa, and roughly one in ten people breathing unsafe air worldwide lives in extreme poverty.8PubMed Central. Global air pollution exposure and poverty In the United States, the disparity is not just about income. An EPA-supported study found that people of color experience above-average exposure to fine particulate matter from emission sources responsible for about three-quarters of total exposure, while white Americans are exposed to below-average concentrations from sources causing about 60 percent of exposure. That gap held across states, across urban and rural areas, and across income levels.9Science Matters. Study Finds Exposure to Air Pollution Higher for People of Color Regardless of Region or Income The correlation between pollution and race has been established so consistently that researchers in environmental economics describe it as a “stylized fact” of social science.10Journal of Economic Perspectives. Environmental Justice: The Economics of Race, Place, and Pollution
Gaps in Who Gets Screened and Who Gets Studied
Insurance is the most obvious gatekeeper to preventive care. Compared with adequately insured adults, women who had never been insured were about 41 percent less likely to receive breast cancer screening and about 47 percent less likely to receive colorectal cancer screening. For men, the gap was even starker: uninsured men were roughly 52 percent less likely to receive colorectal screening.11PubMed Central. Health Insurance Status and Clinical Cancer Screenings Among U.S. Adults These are not rare or specialized tests. They are standard screenings whose whole purpose is catching disease before symptoms appear, and the people least likely to receive them are the ones least able to afford treatment later.
The research that generates medical knowledge has its own diversity problem. The majority of U.S. clinical trials registered over the past two decades did not even report race or ethnicity enrollment data, and among those that did, minorities were consistently underrepresented, with only modest improvement over time.12The Lancet Regional Health – Americas. Demographic representation and results reporting of clinical trials registered in ClinicalTrials.gov between 2000 and 2020: a cross-sectional study A review of barriers to participation found that people from ethnic minorities are frequently underrepresented in randomized controlled trials, the studies that form the basis for treatment guidelines.13PubMed. Why ethnic minority groups are under-represented in clinical trials: a review of the literature Despite the 1993 NIH Revitalization Act, which was supposed to push for broader inclusion in federally funded studies, racial and ethnic minorities remain vastly underrepresented in biomedical research, with real consequences for drug safety, dosing, and therapeutic effectiveness across different populations.14Mayo Clinic Proceedings. Trend Analysis of Minority Representation in Randomized Clinical Trials in the United States
Genomics compounds the problem. Public databases of genome-wide association studies contain far fewer studies of African, Latin American, and Asian ancestral populations compared to European ones.15PubMed. Lack Of Diversity In Genomic Databases Is A Barrier To Translating Precision Medicine Research Into Practice That matters because the risk-prediction tools built from this data perform worse for people whose genetic backgrounds were not well represented in the original studies, which means the promise of precision medicine could widen health disparities rather than close them.16Cell Genomics. Bridging genomics’ greatest challenge: The diversity gap
Mental Health and the Barriers That Come Before Treatment
Mental health care is one of the areas where the gap between underserved and well-served populations is widest. For members of ethnic and racial minority groups, the road to treatment is often blocked by cultural views of mental illness, lack of insurance and access to appropriate services, and a shortage of research on non-white populations.17PubMed Central. Cross-cultural barriers to mental health services in the United States A qualitative study in the United Kingdom identified two broad clusters of obstacles. The first was personal and environmental: difficulty recognizing mental health problems, reluctance to discuss psychological distress (particularly among men), stigma, and financial constraints. The second involved the relationship with providers: long wait times, language barriers, poor communication, cultural insensitivity, and a power imbalance that left patients feeling dismissed.18BMJ Open. Perceived barriers to accessing mental health services among black and minority ethnic (BME) communities: a qualitative study in Southeast England These barriers reinforce each other. Someone who already distrusts the system because of stigma or past experience is unlikely to push through a six-month wait or a provider who does not speak their language.
Medical Mistrust and Its Roots
Distrust of the health care system among underserved groups is often treated as irrational or stubborn. It is neither. Scholars analyzing medical mistrust describe it as a rational and protective response to generations of medical exploitation, including forced breeding, involuntary sterilization, and unethical experimentation.19PubMed Central. Reproductive coercion, medical mistrust, and Black women’s health from the antebellum period to the 21st century Historical trauma from events like the Tuskegee syphilis study and the forced sterilization of minority women has left deep and lasting suspicion toward the medical system in many communities.20PubMed Central. Medical Mistrust: A Concept Analysis Asking why someone does not trust their doctor is the wrong question if you have not first asked what their community’s experience with doctors has been.
Children Falling Behind on Vaccines
Childhood vaccination is one of the most effective public health interventions available, and its coverage is far from equal. A study of a post-COVID-19 birth cohort in the United States found that children from households below the federal poverty line had less than half the odds of being up to date on vaccinations compared to higher-income children. Children who were uninsured had the lowest odds of all, and lower maternal education was also strongly linked to falling behind.21PubMed Central. Socioeconomic Disparities in Childhood Vaccination Coverage in the United States: Evidence from a Post-COVID-19 Birth Cohort In Tennessee, researchers found that lower-income and less-educated parents reported significantly greater barriers related to both accessing vaccines and perceiving them as important, with significant differences across racial and ethnic groups.22PubMed Central. Parental Barriers and Sociodemographic Disparities in Childhood Vaccination Post-COVID-19 in Tennessee The concern is not just that some kids miss a shot. Uneven coverage creates pockets of vulnerability that can allow outbreaks in communities that are already least equipped to handle them.
Older Adults Caught Between Systems
Aging amplifies nearly every barrier that underserved populations face. A systematic review of reviews found that the main obstacles for older adults seeking health and social services are socioeconomic factors on the patient side and geographic factors on the system side, with the digital divide cutting across both.23PubMed Central. Barriers to health, social and long-term care access among older adults: a systematic review of reviews Among elderly Americans who qualify for both Medicare and Medicaid, about a third of those who needed ambulatory or long-term care services in a given year reported experiencing access barriers. African American race, trouble paying for basic living expenses, and poor health were all linked to higher odds of running into those barriers.24PubMed. Access to ambulatory medical and long-term care services among elderly Medicare and Medicaid beneficiaries: organizational, financial, and geographic barriers When long-term care does become necessary, lower-income seniors are substantially more likely to end up in a poor-quality nursing home.25medRxiv. Systemic Review of Health Disparities in Access and Delivery of Care for Geriatric Diseases in the United States
The Digital Divide in Health Care
Telehealth expanded rapidly during the COVID-19 pandemic and was widely framed as a tool to reduce disparities. In practice, it may have widened some of them. A study comparing two communities in rural Illinois found dramatic differences in digital infrastructure. Residents of the more affluent town had average internet download speeds above 130 Mbps, while residents of the economically disadvantaged town averaged around 13 Mbps, barely enough to maintain a stable video call.26SSM – Population Health. The digital health divide: Understanding telehealth adoption across racial lines in rural Illinois The same pattern of fewer working computers, less reliable internet, and slower speeds tracked along racial lines. For communities that were already underserved in person, the shift to virtual care added another layer of exclusion.
LGBTQ+ Patients and Provider Knowledge Gaps
Sexual and gender minority patients face a distinctive set of barriers that often have less to do with insurance or geography and more to do with what happens inside the exam room. A qualitative study involving health care professionals found that even providers who held positive attitudes toward LGBTQ+ patients often lacked the knowledge to deliver appropriate care. The broader culture of heteronormativity in health care systems resulted in inadequate treatment. One concrete example: a transgender patient was misgendered by staff, which led to an insurance billing problem that forced the patient to pay out of pocket for care that should have been covered.27PubMed Central. Assessing LGBTQ+ stigma among healthcare professionals: An application of the Health Stigma and Discrimination Framework in a qualitative, community-based participatory research study Knowledge gaps were worse among older providers, and the systemic issues, like intake forms that do not accommodate non-binary gender, are structural rather than individual.
Indigenous Communities and Chronic Underfunding
American Indian and Alaska Native communities occupy a unique position among underserved populations. The federal government has a treaty-based obligation to provide health services to tribal nations, a responsibility widely understood as “pre-paid” through the massive land cessions of earlier centuries. In practice, the Indian Health Service, which fulfills this obligation, is funded through annual congressional appropriations as a discretionary program rather than an entitlement like Medicare or Medicaid. Its budget has not kept pace with medical inflation or population growth, and long-term underfunding is a recognized contributor to the severe health disparities that persist in these communities.28PubMed Central. American Indian Health Policy: Historical Trends and Contemporary Issues This is not a subtle structural problem. It is a gap between a legal promise and what Congress actually delivers each year.29PubMed. Empirical Evidence and Conceptual Framework to Address the Indian Health Service Underfunding Challenge
People Who Have Been Incarcerated
Incarceration creates a distinctive public health dynamic. Prisons are one of the few settings in the United States where comprehensive health screening is mandated, so diseases like tuberculosis tend to be caught and treated inside. Research found that as the share of formerly incarcerated people in a state rose, tuberculosis rates actually fell, likely because of that systematic testing and treatment.30SSM – Population Health. The contingent effect of incarceration on state health outcomes But for sexually transmitted infections and HIV, the pattern reversed sharply. The same study found that increases in the formerly incarcerated population were associated with large jumps in chlamydia rates for both men and women, and with increased HIV/AIDS mortality. The conditions of incarceration, overcrowding, limited access to prevention, disruption of social networks, appear to amplify transmission of diseases that require ongoing community-level prevention rather than one-time treatment.
What Actually Helps
The Affordable Care Act’s Medicaid expansion offered a natural experiment. In states that expanded coverage, safety-net hospitals saw their uninsured patient stays drop substantially, replaced almost one-for-one by Medicaid-covered stays.31PubMed Central. Early Impact of the Affordable Care Act Coverage Expansion on Safety-Net Hospital Inpatient Payer Mix and Market Shares Insurance expansion does not fix every barrier described above, but it removes the first and most immediate one for millions of people.
Community health workers, people hired from the communities they serve to help patients navigate care, are among the most consistently effective interventions studied. A systematic review found that community health worker programs were effective and cost-effective for certain health conditions, particularly when working with low-income, underserved, and racial and ethnic minority communities.32PubMed Central. Effects of Community-Based Health Worker Interventions to Improve Chronic Disease Management and Care Among Vulnerable Populations: A Systematic Review In a study using electronic health records from two primary care health centers, patients who worked with community health workers showed measurable improvements in blood sugar control, body weight, and cholesterol levels.33PubMed Central. Community Health Worker Impact on Chronic Disease Outcomes Within Primary Care Examined Using Electronic Health Records The reason these programs work is not complicated: they put a trusted, culturally competent person between patients and a system that has often failed them, and that person helps with everything from scheduling appointments to understanding medication instructions to getting a ride to the clinic.
Maternal Health as a Window Into Broader Disparities
Maternal mortality rates in the United States are often cited as a barometer for how underserved populations are faring. The disparities are persistent and, in some cases, worsening. Analysis of U.S. data from 1999 through 2020 found that while maternal mortality rates stabilized among non-Hispanic white and non-Hispanic Black women during the study period, rates among Hispanic women increased at nearly three percent per year.34PubMed. Racial, Age, and Regional Disparities in Maternal Mortality in the USA, 1999-2020 These numbers reflect everything discussed above: unequal access to prenatal care, environmental exposures, insurance gaps, provider bias, and the cumulative toll of chronic stress. Maternal health does not exist in a separate silo from the rest of the health care system. It sits at the intersection of every structural barrier that underserved populations face, which is why it keeps showing up as a signal of broader inequity.