America’s electric grid is made up of more than 450,000 miles of high voltage transmission lines. Comprised of the West, East and Texas power grids, these grids supply more than 140 million customers over industries, businesses and residences with electricity.

We use this electricity every day and often take for granted that it will always be readily available. Sometimes this isn’t the case – for many reasons. Blackouts or power outages occur all the time. Typically, they are quite manageable and get resolved within a few minutes or in less than an hour.

However, there are other instances where this isn’t possible. In these situations, homes and businesses can go without power for half a day to many days. Industries and businesses are greatly affected as well as methods of transportation and communication.

Many areas of the United States have experienced major blackouts or power outages over the years.  Following is a list of 9 of the worst power outages in United States history.

1. Northeast Blackout (1965)

On Tuesday, November 9, 1965 there was a major disruption in the power supply for the Northeast that left over 30 million people without power.

This blackout lasted up to 13 hours and affected many areas of the Northeastern United States including:

  • Connecticut
  • Massachusetts
  • New Hampshire
  • New Jersey
  • New York
  • Rhode Island
  • Pennsylvania
  • Vermont

The major cause of this blackout was human error. A few days before the incident, a protective relay on a transmission line was incorrectly set near Sir Adam Beck Station No. 2, the Niagara generation station in Queenston Ontario.

A protective relay is a critical component to working with electricity. The reason for this is because if it notices a fault, or irregular flow of power, it trips a circuit breaker. When tripped, the circuit breaker provides protection from power overload to an electrical circuit.

The reason why this blackout occurred was because a maintenance worker didn?t set the protective relay high enough. On November 9, the weather was cold, which meant that the power people used to heat, light and cook in their homes, put an incredible strain on the system.

A tiny surge in power, originating from Lewiston New York at the Robert Moses generating plant tripped the relay that was set too low. This deactivated a major power line that was headed for Northern Ontario. The rest of the power flowing to the tripped line was diverted, causing other lines to overload. Each of their relays tripped. With nowhere else to go, the power headed east into New York State and overloaded those lines as well.

This all happened in less than 5 minutes.

The blackout affected many people in many different ways. Most were stranded in office buildings, subway tunnels and trains with no way to get home. Many police officers were called in to help prevent looting and other criminal activities. Some were lucky and never lost power at all. This includes Brooklyn?s Midwood area and Bergen County in New Jersey.

To prevent this situation from happening again, many additional procedures were put into place. Different councils were formed to create standards and share information. The Electric Power Research Institute also helped to create and implement new metering and monitoring systems and equipment, which are still in use today.

2. New York City (1977)

This blackout was caused by a lightening strike on a substation by the Hudson River. It tripped two circuit breakers, which diverted the power in order to protect the circuit. However, this caused 340,000 volts of electricity to convert to a lower voltage for commercial use. A combination of a loose locking nut and slow upgrade cycle stopped the breaker from closing and allowing power to flow again.

A second and third lightening strike caused even more problems. Almost an hour after the initial tripped breakers, New York?s largest power generator went down.

This power outage came at a time of economic struggles, which some blame for the ensuing riots and looting. Many neighborhoods were hit hard, especially Crown Heights and Bushwick. Crown Heights had 75 stores within a 5 block stretch looted, while arsonists forced Bushwick to deal with fires well into the next morning. By the end of the blackout, around 4500 looters were arrested and 550 police officers were injured.

3. West Coast Blackout (1982)

High winds were the cause of this major blackout along the coast of the Western United States. On December 22, these winds knocked a key transmission tower into a line tower causing 3 other towers to fail. More problems occurred when communication issues prevented control instructions from being passed along to workers. Even backup plans failed due to the fact that equipment wasn?t configured to handle such an incredible failure.

It was estimated that around 2 million businesses and homes went without electricity during the blackout, affecting people in San Fransisco and San Diego and all the way to Las Vegas, Nevada.

4. Western North America Blackout (1996)

This blackout actually refers to two blackouts that occurred 6 weeks apart in the same areas. These areas included:

? Western Canada
? Western United States
? Northwest Mexico

It is believed that both power outages occurred because of high demand during incredibly hot summer months in July and August of that year.

The first power outage was caused in Idaho, where there just wasn?t enough electricity. This caused severe voltage instability and the grid failed. Many areas within the United States were affected including, Idaho, Montana, Utah, New Mexico, California and Arizona. Luckily for the 2 million people affected, power was restored with in 1-2 hours.

The second major power outage was caused by the intense summer heat. Many major lines overheated and flashed, grounding to trees and in some cases, starting small fires. Ultimately, in about an hour, Oregon was disconnected from California and Northern California from Southern California. In total, around 4 million people went without power from anywhere between a few minutes to several hours.

While there were few reports of looting and other related damages, many people questioned the utilities role in the outages as well as improper system operations, maintenance, and out of service equipment.

5. North Central U.S. (1998)

On June 25, 1998, a lightening storm in Minnesota struck a line, which caused a transmission failure. A second strike caused cascading transmission line disconnections. Eventually the northern Midwest was separated from the Eastern grid. People went without power for up to 19 hours in areas of the upper Midwest, Central Canada.

6. Northeast Blackout of (2003)

The Northeast Blackout of 2003 is the second most widespread power outage in history. Much larger than the Northeast Blackout of 1965, in America alone, this blackout affected 45 million people in 8 states.

A software bug at FirstEnergy Corporation in Ohio caused this power outage. When overloaded transmission lines hit untrimmed trees, the alarm did not sound to warn maintenance workers. It was a manageable issue that spiraled into a massive problem for the electric grid.

Many states within the United States were affected including:

? Ohio
? New York
? Michigan
? New Jersey
? Vermont
? Connecticut
? Michigan

Most essential services remained operational in most areas, while others failed. Phone services were strained due to the overload in calls. Detroit lost water pressure and were under a water boiling advisory for 4 days after power was restored. Cleveland and New York saw sewage water spill into waterways, forcing many beach closures.

Due to this blackout several changes were made to the national energy policy with a focus on infrastructure protection and homeland security. This was due to the failure of many systems that were used to pick up unauthorized border crossings, port landings and so on.

7. Southwest Blackout of (2011)

This blackout is considered to be the largest in California?s history. It occurred mainly because of the state’s dependence on power imports from Arizona at the time.

At the end of their summer season that year, the continued hot weather caused California’s engineering schedule to conflict with planned outages (for maintenance). This then left the grid vulnerable to human error. A technician switched major equipment, which caused the power to fail for around 12 hours and affect 2.7 million Americans.

The impact to restaurants and grocery stores was devastating. Due to the length of time the power was out they were forced to throw away food at an estimated cost of $12 to $18 million. Several sewage pumping stations also failed, causing the potential for unsafe water in many areas. Since this time, diesel generators were installed at 5 pumping stations.

8. Derecho Blackout (2012)

A derecho is a type of storm that is widespread and long lasting. It is comprised of a series of thunderstorms and can cause hurricane force winds, tornadoes and flash floods. In June of 2012, a powerful derecho moved across large parts of the Midwestern United States, through the central Appalachians and into the Mid-Atlantic states.

The resulting damage caused 4.2 million people across 11 states and the District of Columbia to lose power. In some areas, power restoration took from 7 to 10 days. The areas that were most affected include,

? Ohio
? West Virginia
? Pennsylvania
? West Virginia
? Washington D.C.
? Maryland
? New Jersey

9. Hurricane Sandy (2012)

Hurricane Sandy was a massive hurricane that impacted 24 American states in 2012. These states include,

  • Florida
  • Maine
  • Michigan
  • Wisconsin
  • New Jersey
  • New York

New York was the hardest hit, with flooding streets and subway line closures. Some people even had to go without power for 2 weeks! The damage to New York alone was estimated at $18 billion of the total $17.4 Billion in damages to the rest of the United States.