The analysis also linked other neighborhood characteristics to pharmacy availability. Vehicle ownership, the percentage of single-family homes and median age were associated with an increase in pharmacies per 10,000 people. The percentage of females, higher median household income and the percentage of residents born outside the U.S. were associated with a decrease.

Tracking visits through mobile devices

To understand how people actually use pharmacies, the researchers tracked anonymized movement data from mobile phones. They found that people in predominantly white communities most often visited pharmacies in similar, largely white neighborhoods. Residents of minority communities with fewer pharmacies, by contrast, tended to travel to more diverse neighborhoods to fill prescriptions and access other pharmacy services.

"Our findings show that individuals from predominantly Black and other racial minority areas might prefer to visit pharmacies in diverse neighborhoods if they do not have an available pharmacy," said Dr. Elaine Nsoesie, the study's lead author and an associate professor of global health at BUSPH. She began investigating pharmacy access after writing a 2024 opinion piece in The Boston Globe about pharmacy deserts in Black and Latino communities, which drew a wide range of responses from readers.

Closures affect more than medication pickup

Pharmacies have evolved over recent decades from simple dispensing counters into trusted community health hubs, offering vaccines, testing and treatment for a range of conditions. When a pharmacy closes — or never existed — residents lose access to all of these services at once.

"When a pharmacy is absent in a neighborhood because it closed or was never there, this can create barriers for residents to obtain not only medications but also other essential health services such as vaccines, testing and treatment for multiple diseases and conditions, and other health services," Nsoesie said.

Past data indicate that pharmacy closures have already led to declines in both access to and adherence to lifesaving medications, including cardiovascular drugs and anticonvulsants, which are used to control seizures.

What could fix it

The researchers point to a combination of causes behind the closures: thin profit margins, reduced reimbursement rates for medications and a workforce shortage. Fixing the problem, they argue, will likely require pairing financial reforms with practical local measures.

"Researchers have written about the need to develop policies and financing programs that encourage pharmacies to be located in pharmacy deserts," Nsoesie said. "We suggest that such policies could be coupled with affordable and accessible transportation. However, any long-term solutions should consider the specific needs of the local community to ensure that solutions are effective."

The study's co-authors include Andrew Philips, a research fellow at BUSPH at the time of the study; Dr. Nina Cesare, a research scientist in the Biostatistics and Epidemiology Data Analytics Center at BUSPH; and Zou Yang, then a Ph.D. student at Dartmouth College's Thayer School of Engineering. The analysis relies on mobile device mobility data, which may not capture every population group equally — one limitation the researchers say future work should keep in mind as the pharmacy landscape continues to shift.