The U.S. is connected by one interconnected power grid.

Are All U.S. Power Grids Interconnected?

The U.S. is connected by one power grid consisting of three interconnected grids: the Eastern Grid, the Western Grid, and the Texas (ERCOT) Grid.[1]

Minor Grids

When talking about the whole of North America there are also two other minor grids the Alaska Grid and Quebec Grid (Texas is technically considered a minor grid as well).[2]

A video explaining how the U.S. power grid works.

FACT: The U.S. electrical grid is the largest interconnected machine on Earth. It consists of 450,000 miles of high-voltage transmission lines and 5.5 million miles of local distribution lines, linking thousands of generating plants to factories, homes and businesses.[3][4]

How Does the U.S. Electrical Grid Work?


450,000 miles of high-voltage transmission lines connect the grid, consisting of two major and three minor grids. The power transferred through these lines originates at power plants placed across the country.

How Power Plants Power the Grid

Electricity is moved from power plants through the grid, either locally or nationally; by independently run control centers that monitor power needs and control the energy flow in real time. Energy can’t currently be stored effectively on a large scale, so the supply and demand of power has to be constantly balanced with electricity moving through the grid as needed.

AC / DC and Transformers

Transformers are used to connect the grid and transfer power between high voltage and low voltage lines.

Direct Current (DC) is used to transfer power through high voltage lines and Alternating Current (AC) is used to distribute power through local lower voltage lines.

The power is switched between high and low voltage using transformers. This is because high voltage direct current is useful for transferring power, while locally mostly low voltage alternating current is needed as a local power source for factories, homes, and businesses.


The two major and three minor grids are overseen and controlled by nine regional, non-governmental, “self-regulatory organizations”. Eight of these are organized under the NERC (North American Electric Reliability Corporation) and the other is the west coast’s WECC (Western Electricity Coordinating Council). All of these entities are groups of experts and industry leaders that take on a number of roles related to the North American grid. One of the core roles of these entities is controlling the flow of power as needed throughout the grid.

Is Having a Single Interconnected Grid Dangerous?

The power grid was built over a hundred years ago and a lot of the infrastructure is over fifty years old. The current grid is vulnerable to weather, natural disasters, Electro-Magnetic Pulse (EMP) weapons, and cyber attacks.

A video from Fox News explaining potential threats of cyber attacks on the grid.

The threats posed to our current system are real. That is why it is so important for us to fund new energy development and innovations. It’s also why something called the “smart grid” and other solutions (like burying power lines instead of having them hanging in the air) are being proposed.

FACT: The U.S. is connected by one grid. The idea is to make it a “smart grid”. The smart grid would be part of the Internet of Things (IoT) which can use cognitive computing to replace the need for human micromanagement of the grid. This could greatly optimize how the grid works.

The Smart Grid (and Other Solutions)

In it’s simplest form the smart grid just means using technology to convey data about energy needs between homes, businesses, factories, transformers, controllers, and power plants. Having the grid be interconnected in a smarter way allows newer and more efficient technologies to integrate into the grid (like better solar and wind generation and like smart appliances in the home).

A video answering the question: “What is the smart grid?”.


Right now there is no way to efficiently store energy on a large scale. Controllers turn power plants and on and off as needed. Batteries could help store energy (so, for instance, wind turbines wouldn’t need to be turned off during a wind storm), while a smart grid could better direct power to eliminate energy waste.

Currently we run efficient sources at “peak times” to meet energy demand and waste potential energy and non-peak times. It also means energy costs more at peak times.

Reducing Power Outages

By better communicating a smart grid could help eliminate power outage times by rerouting power through a different set of lines.

Reducing Power Outages

By better communicating a smart grid could help eliminate power outage times by rerouting power through a different set of lines.

Reduce Fuel Usage and Costs

Electric vehicles can be connected to the grid to make us less dependent on fossil fuel and provide us with a cheaper source of energy to fuel transportation. This is current technology.

Problems with the Smart Grid

The benefit of having an interconnected smart grid may be seen as being offset by dangers. A smart grid is vulnerable to security threats, EMPs, and natural disasters. It is however, better equipped to deal with some of the potential problems, namely weather related problems. The smart grid is a loose term; the core idea is improving our grid with security threats in mind.

What Should be Done about the Grid?

A truly “smart” grid will take steps to protect against EMPs, cyber attacks, and natural disasters and not just focus on using the technology of the day to better manage the grid.

Although the grid as a whole is vulnerable, proper funding and innovation can now offset this danger. The more “energy” we put into improving the grid, the better prepared we will be to deal with disaster.

We have to seriously ask ourselves questions like: Is the fact that the grid is run by private companies hindering our progress in energy development and thus jeopardizing national security? Consider the DoD (Department of Defense) uses the grid for almost all of its power.

You can see some of the actions that are being taken to secure the grid at… securethegrid.com.

In the Meantime, Local Grids and Local Energy Sources are a Good Idea

One thing we can do locally, i.e. without the need of reforming the entire grid, is to focus on ensuring self-contained local grids that can run local cities and communities in the event of disaster.

Newer technologies like solar panels can help to power a backup grid or even power a community for a short period of time. By protecting ourselves locally we can as communities help ensure that we can retain some semblance of power and communication in the event of being disconnected from the major and minor grids in case of an emergency.

On this same note, we should also be taking the idea of creating self-contained intra-nets within cities. Again, we have to ask ourselves, “At what point does the role that private companies are playing in our power and communication jeopardize our future as communities in the event of a disaster?” The earlier we embrace “smart” energy ideas that strengthen America’s national security the better.


What we should do about energy is a pressing and complex issue. There are a lot of different moving parts to this puzzle. Consider reading Ted Koppel’s book as reviewed in the New York Times, doing your own research, and sharing your findings with the FactMyth.com community.


The U.S. is connected by one power grid consisting of 2 major and 3 minor grids.


  1. Simple, Fast Facts on America’s Electric Grid & Infrastructure“. Electricchoice.com. Nov 21, 2015.
  2. Western Interconnection“. Wikipedia.org. Nov 21, 2015.
  3. U.S. Electrical Grid Undergoes Massive Transition to Connect to Renewables“. Scientificamerican.com. Nov 21, 2015.
  4. Top 9 Things You Didn’t Know About America’s Power Grid“. Energy.gov. Nov 21, 2015.

"The U.S. is Connected By One Power Grid" is tagged with: Electricity, Energy, Systems, United States of America

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michael t. on
Doesn't beleive this myth.

I just imagine our powerful nation as it is, the highest technology at this point in time being so volurnable to any threat by any one.m

Thomas DeMichele
Thomas DeMichele on

It is a little absurd.