PlainEnviro

Top 10 US Counties by EPA-Reporting Industrial Facilities

PlainEnviro ranks all 2,600+ US counties by the count of EPA Toxics Release Inventory reporting facilities. The ranking reflects the most recent EPA TRI data release.

Research period:

Compiled by PlainEnviro on 2026-08-25

Research question

Among 2,600+ US counties, which host the largest count of EPA TRI reporting facilities, and how does facility concentration overlap with Superfund site presence and drinking-water system count?

Methodology

This ranking is built directly from the U.S. Environmental Protection Agency’s published environmental data, ranking 2,600+ US counties by the number of EPA Toxics Release Inventory (TRI) reporting facilities each one contains. Every figure shown is taken straight from the EPA’s release – nothing is hand-entered, estimated, or adjusted beyond display formatting – and each number is auditable back to its source record through the links in the table.

Counties with no reported value on the ranking metric are left out rather than shown as zero, so the list reflects only the counties the EPA actually reports activity for. The EPA occasionally suppresses individual values for confidentiality or data-quality reasons; those records are excluded here by design rather than displayed as zeros. Values appear exactly as the EPA publishes them, with thousands separators added only for readability.

The figures reflect the most recent EPA data release we have processed. When the EPA publishes a revision, the updated values flow through to this page automatically, so there are no hand-copied numbers to fall out of date. Alongside the top ten, we show whole-population context – the total number of counties reported and the average facility count – so you can see how concentrated the top of the distribution really is.

See the methodology page for the full source list, data vintages, and how each metric is defined.

Top 10 US Counties by EPA-Reporting Industrial Facilities

Counties ranked by EPA-reported TRI facility count

facilities

What this shows Facility count tracks industrial-corridor concentration, not per-capita risk; the leading counties host major ports, refineries, and chemical clusters.

Source U.S. Environmental Protection Agency As of 2023

The ranked top 10

All 10 ranked counties, drawn directly from the EPA dataset.

# County State TRI facilities Superfund sites
1 Harris TX 434 16
2 Los Angeles CA 399 19
3 Cook IL 350 4
4 Maricopa AZ 220 7
5 Cuyahoga OH 163 1
6 Tarrant TX 161 3
7 Dallas TX 154 4
8 Wayne MI 140 4
9 Milwaukee WI 129 2
10 Orange CA 128 4

Source: U.S. Environmental Protection Agency, EPA TRI / SDWIS / Superfund county rollup. Figures are drawn directly from the EPA release and refresh when the EPA publishes an update.

Findings

Top entity in the ranking

The top-ranked record in this dataset is Harris, with a value of 434 on the TRI facilities column. The full top-10 set is rendered in the table above. Every value is drawn directly from the EPA data. When the source agency publishes a revision, the ranking and the text around it update automatically.

Distribution shape

The top-ranked county, Harris, reports 434 TRI facilities – about 3.4× the 10th-ranked county (128). The leading counties are highly concentrated: a handful of industrial corridors host a disproportionate share of the reporting facilities. 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 all 2,531 reporting counties, the combined facility count is 25,986, an average of 10 facilities per county. The top-10 counties shown above account for 8.8% of that combined total. Counties with no reported value are excluded from these totals, exactly as they are from the ranking. These totals are computed across the same EPA dataset shown in the ranking.

Source provenance

The records in this ranking originate from U.S. Environmental Protection Agency, specifically the EPA TRI / SDWIS / Superfund county rollup. PlainEnviro presents the EPA’s published release here unchanged except for display formatting. Because the figures are drawn directly from that release, a revised EPA dataset propagates to this page automatically, with no stale hand-copied numbers. The methodology page documents the source URL, the vintage date, and how the data is prepared.

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

County-level facility counts reflect the location of the facility's industrial address as reported to the EPA, not necessarily the operating company's headquarters or the location of downstream environmental effects. Counties with major industrial corridors (port facilities, refineries, chemical clusters) will rank high on facility count without that count implying per-capita environmental risk. Water system counts include very small community and non-community systems alongside large urban utilities, count alone does not indicate population served. Superfund site counts reflect active NPL placement; many counties have additional brownfield, state-led cleanup, or post-deletion sites not captured here.

Secondary cut from the same source

Top 10 counties by Superfund (National Priorities List) site count

Superfund sites

What this shows Superfund site count reflects active National Priorities List placement; it excludes pre-NPL, deleted, and separately-authorized cleanup sites.

Source U.S. Environmental Protection Agency As of 2023

Related data

Sources