Fig. 2 Data is sourced from the National Library of Medicine at clinicaltrials.gov and include trials with a status of recruiting, not yet recruiting, active, or not recruiting. Accessed May 2025.
Which states have the most clinical trials?
As expected, population density is a significant contributing factor in the geographic distribution of clinical trials across the U.S. Greater patient volumes, after all, increase the likelihood of finding eligible participants for clinical research. For this reason, we see a strong correlation between those states with the largest populations and the highest reported clinical trial volumes—including California, Texas, New York, and Florida.
Though it’s not explicitly represented on the above map, there also appears to be a strong correlation between high clinical trial volumes and facility types—where states with high-performing cancer centers, academic medical centers, or other research facilities report greater volumes of clinical trials than areas with fewer numbers of these facility types.
Massachusetts, Pennsylvania, and Ohio, for instance, all rank highly for active clinical trials, and are also in the top five for most academic medical centers in the country.
Top hospitals by clinical trial volume
| Rank | Hospital name | Definitive ID | Location | Number of clinical trials |
| 1 | Mayo Clinic | 7104 | Rochester, MN | 6,438 |
| 2 | University of Texas MD Anderson Cancer Center | 4017 | Houston, TX | 6,399 |
| 3 | Massachusetts General Hospital | 1973 | Boston, MA | 5,656 |
| 4 | Memorial Sloan Kettering Cancer Center | 2846 | New York, NY | 4,233 |
| 5 | Duke University Hospital | 2973 | Durham, NC | 3,705 |
| 6 | Dana-Farber Cancer Institute | 1978 | Boston, MA | 3,550 |
| 7 | Vanderbilt University Medical Center | 3742 | Nashville, TN | 3,352 |
| 8 | National Institutes of Health Clinical Center | 581811 | Bethesda, MD | 3,234 |
| 9 | University of Pittsburgh Medical Center (AKA UPMC) | 6448 | Pittsburgh, PA | 2,782 |
| 10 | Brigham and Women’s Hospital | 1969 | Boston, MA | 2,618 |
Fig. 3 Data from the Definitive Healthcare Atlas Dataset and sourced from The Clinical Trials Transformation Initiative (CTTI). The total number of clinical trials includes all historically reported. Accessed May 2025.
Clinical studies can be sponsored by a number of different agencies, ranging from industry organizations like pharmaceutical companies to academic medical centers or federal agencies—including the National Institutes of Health, the U.S. Department of Defense, and the U.S. Department of Veterans Affairs.
While clinical studies can be conducted in a variety of different locations, access to specific equipment, physician expertise, or sample patient populations quite often influence this decision. With greater access to these critical resources, places like cancer research facilities and university medical centers are frequently selected as locations for hosting clinical trial research.
In fact, all 10 of the top hospitals by historic clinical trial volume are cancer research centers, university hospitals, or another type of dedicated research facility, according to Definitive Healthcare data.
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