How did segregation in the US affect blood donations?

When the US established its first nationwide network of blood banks in 1941 with the hopes of restoring the dwindling reserves of military members, it was quick to emphasize blood donated by Black Americans wouldn't coat the veins of white servicemen. Historians say this policy was meant to appease white Southerners who believed Black blood was inferior to their own.This policy was leaked to the press that same year.

Explore this blood type interactive to learn more about how the 8 most common blood types are defined.

'Golden blood' is the rarest blood type in the world—fewer than 50 people are known to have it.

An interactive explanation of blood transfusion

The antigens and Rh factors of blood cells (which determines your blood type) must be compatible with your immune system—which is why blood transfusions between patients must have matching types. In a mismatch, the immune system will attack and destroy donor blood cells, triggering a potentially fatal reaction.

Without the option of modern blood transfusions, some doctors in the mid-1800s tried to help save cholera patients by injecting them with cow's milk, hoping it would boost their nutrition and hydration.

Why don't we synthesize blood?

We're trying. Scientists are currently working on creating viable synthetic blood, an alternative to the presently relied-upon donations that manage to fall short of demand. More than half of the world's nations struggle to meet their population's need for blood. This article details current and historical efforts to develop synthetic blood, a venture that started more than 400 years ago.

A brief history of human blood groups

The blood group that determines whether you have type A, B, AB, or O blood was discovered near the turn of the 20th century. This short academic article dives into three main theories about the evolution and emergence of blood groups, the exact nature of which remains unclear.

Each second, the human body produces 2 million to 3 million new red blood cells.

Seven things you might not know about blood

The red stuff currently pumping throughout your body is a type of connective tissue that is both a solid and a liquid. The liquid portion—plasma—acts as a carrier for the solid portion, which includes blood cells and their biological brethren. Your body is constantly refreshing its supply of blood, creating new cells to replace those that have expired or died. This article overviews some lesser-known facts about blood (and why it's not always red).

The proteins and sugars on the surface of your blood cells determine your blood type.

In 2023, the FDA approved gene therapy for sickle cell disease, enabling one-time infusion bespoke treatments that use a patient's own stem cells to effectively cure a painful condition that disproportionately affects people of African American descent.

How much your blood really costs

In the US, donating plasma twice a week can earn you $400 a month. But this system only works by targeting people who need the money most. Plasma clinics are placed in low-income zip codes, and frequent donation may increase health risks.

New blood cells are created by hematopoietic stem cells

Blood is made up of several cells with various functions and short lifespans, so the body must have a constant supply of replacements. These replacements are created by hematopoietic stem cells, rare cells that live in bone marrow and can regenerate themselves and blood cells.

The ultrarare 'Er' blood type has been documented only about 40 times, and it can cause devastating pregnancy complications.

A robot can now stand in for a phlebotomist and draw blood from adult patients after the FDA approved the device in August 2026.

3 US maps illustrate transplants, donors, and organ waitlist additions—by state.

A stroke occurs when blood flow to part of the brain is suddenly interrupted, either by a blockage (ischemic stroke) or bleeding when a blood vessel in the brain breaks and bleeds (hemorrhagic stroke).

In 2024, the US had more organ transplants than ever before—besting the 2023 record

More than 48,000 organ transplants were performed in 2024, and about 46,630 were performed in 2023. These record highs are illustrated here as part of data from 1988 to partway through 2025. Kidneys, livers, and the heart remain the most common transplanted organs. (Some users may encounter a paywall.)

The strange endurance of consuming blood for health

Blood's importance to humanity is best summarized this way: without it, we die. This importance naturally begets assumptions about its medicinal properties, many of which appear accessible through drinking or eating the fluid connective tissue. This article details the history of blood drinking, from ancient Roman gladiators to modern-day sanguinarians.

'Donation after circulatory death' is on the rise

This occurs when a patient in a coma is on life support and family members agree to donate the organs. Watch this video about a 2025 New York Times investigation that identified 12 instances across nine states of bungled or premature attempts to retrieve organs from people whose families had authorized withdrawal of life support.

The economics of horseshoe crab blood

Horseshoe crabs are older than dinosaurs and have survived five mass extinctions that wiped most life from the planet. But it's only now that their future as a species is in danger. This blood, worth about $60,000 per gallon, is hyper-sensitized to certain bacteria that are fatal to humans. This 17-minute podcast dives into humanity's pursuit of horseshoe crab blood, a "somewhat magical" mixture heavily relied on by the pharmaceutical industry.

There may be a surplus of nearly 8,000 emergency room doctors by 2030

That was the 2021 prediction of the American College of Emergency Physicians, which led to a sudden steep decline in the field among medical students and residents. (Some users may encounter a paywall.)

The history of blood, as told by a hematologist

Since ancient times, blood has been seen as a semi-magical substance. Alchemists theorized it was a mixture of the four elements. Others proposed it was one of four bodily fluids whose balance dictated health. This 2019 essay by a hematologist reviews blood's reputation across cultures and centuries.

When was the first blood transfusion?

In the 1600s, an English doctor transferred the blood from one dog to another via quills. The procedure ended when one of the dogs died. This article details the early days of blood transfusions, which turned toward humans shortly after the 1666 dog experiment and involved putting the blood of a sheep into a human recipient (who reportedly survived the encounter).

In 2023, the US money supply fell at its fastest rate since the 1930s

The money supply tracks how much cash, as well as electronic funds like savings accounts, is circulating through the economy. And a downward turn can be a bad sign.

Environmental conditions, shifting immunity, and viral strain could help explain 2025 spike

The surge in HFMD in the summer and early fall of 2025 in the mid-Atlantic could be the result of a confluence of factors, including a more virulent strain of disease-causing virus, good environmental conditions for the virus to spread—hot, humd—and a potential immunity gap among kids due to milder HFMD outbreaks the previous year.

Using stem cells for bone marrow transplants

Stem cells hold promise for many future medical applications, but only one type of stem cell is currently approved for use. This page offers a clear description of adult stem cells called hematopoietic stem cells, which create the full range of blood cells and are approved for use in treatments such as bone marrow transplants.

The COVID-19 pandemic led to a decrease in immunizations in the US and worldwide

Public health funds and resources that were diverted to COVID-19 response reduced efforts to combat polio and vaccinations for polio and other diseases declined during the pandemic, putting more people at risk for polio.

Blood has evolved many times over hundreds of millions of years, resulting in different blood colors and compositions—and there are even some organisms that don't need blood at all.

The 2026 Ebola outbreak is hampered by a lack of vaccine against the relevant species of the virus, heightening the need for rapid tests to aid in disease control.

White patients waited 374 days for a kidney—Black patients waited 727 days

A 2022 congressionally mandated report highlighted racial inequities in the US organ transplant system, including disparities that made it more likely white people will be placed on organ wait lists than Black people. It spotlighted inequities such as racial differences in median kidney wait times identified in earlier research. The report, from the National Academies of Sciences, Engineering, and Medicine, recommended fixes including that the Department of Health and Human Services develop national performance goals for the system and achieve equity in the system in the next five years.

Hemorrhagic strokes make up roughly 13% of stroke events

A hemorrhagic stroke occurs when a faulty blood vessel within the brain bleeds. Though this is less common than an ischemic stroke, it is often far more deadly. This in-depth resource from the American Stroke Association provides a comprehensive overview of the two main subtypes of hemorrhagic stroke along with a useful animation of the condition.

Cities bore the brunt of the migrant surge in the 2020s

During the 2022-24 migration surge, cities such as New York, Chicago, and Denver faced shelter overcrowding, strained public services, and housing shortages—while the upfront costs fell almost entirely to states and cities.

The first CRISPR-approved treatment was for sickle cell anemia in 2023

Victoria Gray was the first patient to receive a CRISPR-based therapy, which eliminated her symptoms and restored her health. The therapy's initial cost of $2.2M has kept it out of reach of many patients.

The Atlantic proclaimed that 'The End of Reading is Here,' which might be alarmist but is based on significant data.

As of February 2025, there are more than 150 clinical trials using CRISPR technology

The clinical trials are designed to determine whether experimental CRISPR-related therapies are safe and effective. The majority of trials involve treatments for blood disorders, including beta thalassemia.

America's top causes of death are heart disease, cancer, accidents, and stroke

Heart disease killed more than 680,000 people in 2023 and cancer killed around 613,000 people that year. Both causes of death are far above the next leading cause of death—accidents, which numbered around 223,000. Provisional data for 2024 indicates the leading causes of death remained the same.

How did the pandemic affect mental health?

Read this research brief to learn more about why heightened mental health and substance use concerns persist three years after the outbreak of COVID-19. According to a recent survey, the vast majority of American adults view the nation as facing a...

Explore the microscopic composition of blood.