LEARN / REINDUSTRIALIZATION

What Is the Electric Grid?

There is no single American electric grid. There are three synchronous systems that barely exchange power, operated by roughly seventy separate balancing authorities, with a market layer of seven regional operators laid across them. Which of those three things a claim refers to usually goes unstated.

Key points

The contiguous United States runs on three interconnections: Eastern, Western and ERCOT, which operate independently with very limited transfer between them.
The Eastern Interconnection contains 36 balancing authorities, the Western 37, and ERCOT exactly one.
Balancing authorities operate the system in real time. Regional transmission organisations run markets. The two are different functions and only sometimes the same organisation.
ERCOT is uniquely all three at once: the interconnection, the balancing authority and the regional operator are one entity.
For an industrial siting decision, the question is never “can the grid supply this.” It is which balancing authority, and what that particular one requires.

Three systems, not one

The Energy Information Administration describes the physical system in three parts. The Eastern Interconnection covers the area east of the Rocky Mountains plus a portion of northern Texas. The Western Interconnection runs from the Rockies west. The Electric Reliability Council of Texas covers most, though not all, of Texas. Each operates as a single large synchronous machine, with every generator inside it turning in step with every other.

That synchrony is why the boundaries matter. Two interconnections cannot simply be joined with a wire, because their alternating currents are not in phase, and moving power between them requires direct-current equipment installed for the purpose. The transfer capability that exists between the Eastern and Western systems is small relative to the load either one carries.

Data36 · 37 · 1
Balancing authorities in the Eastern Interconnection, the Western Interconnection and ERCOT. The Eastern total is 31 in the United States and 5 in Canada; the Western is 34 in the United States, 2 in Canada and 1 in Mexico. Source: U.S. Energy Information Administration.

Series and provenance

Agency: U.S. Energy Information Administration
Program: Today in Energy
Series: U.S. electric system interconnections and balancing authorities
Measure: Count of balancing authorities by interconnection
Units: Count of entities
Period: Structural description rather than a time series
Latest: Eastern 36 (31 U.S., 5 Canada); Western 37 (34 U.S., 2 Canada, 1 Mexico); ERCOT 1
Source tier: Primary
Retrieved: August 9, 2026

Counts change as balancing authorities consolidate or form. Interconnection, balancing authority and regional transmission organisation are distinct concepts, and ERCOT is the single case where all three are the same entity.

Open the source

What a balancing authority does

EIA describes the balancing authority as the entity that ensures, in real time, that demand and supply are finely balanced. If they fall out of balance, local or wide-area blackouts follow. Most balancing authorities are utilities that took on the responsibility for a portion of the system, and they are connected to one another by metered high-voltage tie lines.

This is the operating layer, and it is the one that matters for a new industrial load. The study that determines whether a facility can be served, what upgrades it must pay for, and how long that takes is run by the balancing authority or the transmission owner in its footprint, not by anything called the grid.

What a regional operator does

Independent system operators and regional transmission organisations came out of two Federal Energy Regulatory Commission orders: Order No. 888 in 1996, which opened transmission access and established the foundation for organised wholesale markets, and Order No. 2000 in 1999, which encouraged utilities to join regional transmission organisations. Seven now operate in the contiguous United States and together serve roughly two-thirds of national load.

Their function is market operation and transmission planning across a footprint, which is a different job from second-by-second balancing, even though the same organisation frequently performs both. In the roughly one-third of the country outside an RTO, wholesale arrangements are bilateral and the planning process looks different.

Measurement noteInterconnection, balancing authority and regional transmission organisation are three distinct things and are used interchangeably in most coverage. NERC adds a fourth layer, assigning compliance responsibility to six regional entities. ERCOT is the source of much of the confusion, because there the interconnection, the balancing authority and the regional operator are the same entity, which makes it the one case where the terms genuinely are synonyms.

Why the distinction binds industrial siting

A firm evaluating two sites four hundred miles apart may be evaluating two entirely different regulatory environments, two different queue processes, two different sets of upgrade cost allocation rules and two different market structures, without either site appearing different on a national map. Whether the sites sit in the same interconnection determines whether power can physically be moved between them at scale. Whether they sit in the same balancing authority determines who studies the request.

Institute analysisCoverage of industrial power constraints is usually written at national scale, and almost every operative decision is made at balancing authority scale. A national figure for queue duration or reserve margin describes an average across systems that do not share a queue, a market or, in two cases out of three, a synchronised alternating current.

Common misconceptions

That the United States has a national grid. It has three synchronous systems with limited transfer between them. Power surplus in one interconnection is not straightforwardly available to another.

That an RTO operates the grid. An RTO operates a market and plans transmission across a footprint. Real-time balancing is the balancing authority function, which an RTO often also performs and sometimes does not.

That ERCOT is a market design choice. ERCOT is first a physical fact. Its limited synchronous connection to the rest of the country is what makes its separate regulatory position possible.

What the evidence says, and where it is contested

ContestedWhether to build substantially more interregional transfer capability is disputed. One position holds that greater transfer between interconnections would let surplus in one region serve scarcity in another, improving reliability and lowering cost. A second holds that the direct-current equipment required is expensive, that cost allocation across regions has no settled method, and that regions reasonably resist paying for capability whose benefit accrues elsewhere. The physical case and the institutional case point in different directions, and the institutional one has prevailed for decades.

Related Institute research

Why Reindustrialization Requires More Electricity
Why a factory buys firmness rather than annual energy.

What Does It Take to Reindustrialize America?
Where energy sits among the nine inputs.

Sources

U.S. Energy Information Administration, “U.S. electric system is made up of interconnections and balancing authorities,” Today in Energy. eia.gov
Federal Energy Regulatory Commission, Western Energy Markets Explainer, including FERC Order No. 888 and Order No. 2000. ferc.gov
North American Electric Reliability Corporation, 2025 Long-Term Reliability Assessment, January 2026. nerc.com
U.S. Energy Information Administration, Electricity data. eia.gov

Reference entry maintained by the Institute for American Manufacturing & Technology. Figures are drawn from primary sources and cited above. Where the Institute states a position rather than a finding, it is marked as such.