Top 10 US States by Clinical Trial Site Count
PlainTrial ranks US states by the number of clinical trials with at least one trial site located in the state, using the states aggregate. Updated automatically as new data is processed.
Research period:
Research question
Across the 50 US states and the District of Columbia, which jurisdictions host the largest number of clinical trial sites, and how does the share of trials currently recruiting in each state compare to the cumulative total across all trial statuses?
Methodology
This ranking reflects the data currently in our database, sourced from the agency referenced in the citation below and updated automatically as new filings are processed.
Coverage and exclusions: the source agency occasionally suppresses values for confidentiality, small sample size, or quality control, and suppressed rows are excluded from this ranking rather than shown as zero. If the agency later revises a figure, the revised value replaces the old one automatically the next time our data is refreshed.
Data provenance: we pull each release as it becomes available and normalize it into our database; a later release simply supersedes the one before it, so readers never see a mix of old and new figures on the same page.
Comparability across years: when the source agency revises its release schedule, definitions, or coverage, we note the affected years on the methodology page so readers can compare like-with-like rather than across a changed measurement.
Editorial governance: a named editor reviews every ranking page before publication (see the byline above). If an entity disputes a figure attributed to it, corrections are checked against the official source record before any change is made.
Every number on this page can be traced back to its source by following the entity links and the citation below, so independent verification never requires anything beyond the original public source.
See the methodology page for the complete data-update process, source vintage, and field definitions.
Top 10 US States by Clinical Trial Site Count
Live data: reflects the current dataset
The ranked top 10
Every row below reflects the current 10-record dataset. Reload the page after new data is processed to see the latest values.
| # | State | Trials with site | Recruiting trials |
|---|---|---|---|
| 1 | California | 16,646 | 5,482 |
| 2 | Florida | 10,986 | 3,625 |
| 3 | New York | 10,554 | 3,675 |
| 4 | Texas | 9,951 | 3,731 |
| 5 | Massachusetts | 7,667 | 2,710 |
| 6 | Pennsylvania | 6,946 | 2,373 |
| 7 | Illinois | 6,854 | 2,290 |
| 8 | Ohio | 6,514 | 2,298 |
| 9 | Maryland | 6,441 | 2,178 |
| 10 | North Carolina | 5,625 | 1,847 |
Source: U.S. National Library of Medicine, ClinicalTrials.gov Registry (state site aggregates). Values reflect the current dataset, refreshed as new filings are processed. U.S. National Library of Medicine, ClinicalTrials.gov Registry (state site aggregates). Values reflect the current dataset, refreshed as new filings are processed.
Where recruitment is open right now
Total site count measures cumulative research presence; the currently-recruiting count below shows where a participant could actually enroll today. The two orderings differ, a state can host many completed studies yet few open ones.
Recruiting Trials by State (Top 10 by Total Sites)
Currently-recruiting trials with at least one site in each state, live query at request time
Findings
Top entity in the ranking
The top-ranked record in this dataset is California, with a value of 16,646 on the Trials with site column. The full top-10 set is rendered in the table above. Every value comes directly from the current dataset; no number is hardcoded into this page. When the U.S. National Library of Medicine publishes a revision, the ranking and the prose around it update automatically.
Distribution shape
The gap between the top-ranked record (16,646) and the 10th-ranked record (5,625) characterizes how concentrated the top of the distribution is. Where the top value is many multiples of the median value of the visible set, the population is highly concentrated, a small number of entities accumulate the bulk of the measured quantity. Where the top and bottom of the visible set are close together, the distribution is relatively flat across the top end. The full distribution beyond this top-10 cut is summarized in the aggregate context section below and explored in the linked entity profiles.
Aggregate context
Across the full population behind this ranking, here are the summary statistics: how many records exist in total, the sum of the ranking metric across all qualifying records, and the mean per-record value. The methodology page documents the exact filter applied (records with null or zero values on the ranking metric are excluded). This aggregate row is computed from the same dataset that powers the ranking above.
Source provenance
The records in this ranking originate from U.S. National Library of Medicine, specifically the ClinicalTrials.gov Registry (state site aggregates). PlainTrial ingests the source vintage published by the agency and keeps this page current, there is no static export carrying stale numbers, and a newly published dataset is reflected here within hours. The methodology page documents the source URL, the vintage date, and the steps applied to prepare the data.
Why this ranking matters
Rankings like this one let a reader scan a population quickly and identify outliers, concentrations, and patterns that warrant deeper investigation. The detail pages linked from each entity in the table above give the full per-entity context: time-series history where available, related metrics from adjacent tables, and links onward to the underlying source records. The methodology page explains how an entity earns inclusion in the dataset and how the ranking column is computed at the source.
What this analysis cannot tell us
A single trial that operates across multiple states is counted in each state hosting a site, so the sum of per-state counts exceeds the total number of distinct trials in the registry. State trial counts therefore reflect both the underlying intensity of trial activity in the state (large academic medical centers, NIH-funded research universities, industry clinical operations) and the prevalence of multi-state trial designs that span many sites. International trials with no US enrollment site do not appear in state counts even if they otherwise touch US researchers or US-based sponsors. The recruiting count reflects the trial-level status as reported by the sponsor, not the site-level recruitment status, so a state may show a trial as 'recruiting' even if the specific site in that state is no longer actively enrolling participants.
Sources
- ClinicalTrials.gov - https://clinicaltrials.gov/
Every figure on PlainTrial is rendered directly from the ClinicalTrials.gov registry, no number is typed in by an editor. This ranking sorts states by total registered trial count, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, the data changelog, or report a data error.