Longest Power Outages in U.S. History, Ranked by Duration

On August 11, 2026, a derecho with 99 mph winds tore through northwest Indiana, knocking out power to more than 301,000 NIPSCO customers. Fourteen days later, nearly 5,000 homes in Gary, Indiana, are still without electricity — making it one of the longest non-hurricane power outages in a U.S. city in recent history.

Most rankings of major outages, including ours, focus on the number of people affected. But the question that Gary raises is different: how long is too long?

This is a ranking by duration — the outages where the last customers waited the longest to get their lights back on.

Duration = time from storm onset to last customer restored. Most customers in each event had power back much sooner.

1. Hurricane Maria — 328 Days (2017)

The longest blackout in U.S. history, by an enormous margin, was Hurricane Maria’s destruction of Puerto Rico’s electrical grid. The Category 4 storm hit on September 20, 2017, and knocked out power to all 3.4 million residents. PREPA (the Puerto Rico Electric Power Authority) did not restore the last households until mid-August 2018 — 328 days later.

The scale of infrastructure damage was almost without precedent: 80% of the island’s power lines were destroyed. Rural mountain communities were the last to be reconnected, with access roads themselves requiring months of work. The U.S. Army Corps of Engineers mounted the largest power-restoration mission in its history. An estimated 2,975 people died, many from lack of medical care during the extended outage.

“A video published by El Nuevo Día showed members of one family crying, cheering and clapping as they turned on a lamp in their home for the first time in 11 months.”
— Vox, August 15, 2018

2. Hurricane Katrina — 4+ Months (2005)

Katrina didn’t just knock down power lines — it physically demolished the grid across southeastern Louisiana and the Mississippi Gulf Coast. Transmission towers were twisted, substations submerged, and entire distribution networks had to be rebuilt from scratch. Mississippi Power restored all customers who could accept power within 12 days. New Orleans was a different story entirely.

Two months after landfall, 40% of New Orleans homes were still without power. In November 2005, under mounting pressure from city officials, Entergy pledged to restore power to all New Orleans customers by the end of the year — roughly four months after the storm. Some individual homes in the Lower Ninth Ward and eastern New Orleans were not reconnected until 2006, more than a year later.

What makes Katrina’s duration harder to measure than any other event on this list is that much of the territory was uninhabitable. Restoration couldn’t proceed until floodwaters receded, structures were inspected, and residents were allowed to return. In some neighborhoods, “restoration” meant building a new grid, not repairing the old one. There is no single “last customer restored” date.

3. Hurricane Laura — 34 Days (2020)

Laura’s eye wall passed directly over Lake Charles, Louisiana, on August 27, 2020, with 150 mph winds. The storm caused catastrophic damage to transmission infrastructure — not just distribution lines, but the high-voltage backbone that feeds power into the city. Entergy couldn’t begin restoring individual customers until transmission lines were physically rebuilt.

Entergy set an official completion date of September 30 for all customers who could safely receive power — 34 days after landfall. That target was confirmed met before Hurricane Delta struck the same region on October 9. Rebuilding the transmission system itself continued through November.

4. Hurricane Ida — 31 Days (2021)

Ida made landfall near Port Fourchon, Louisiana, on August 29, 2021, as a high-end Category 4 hurricane. It knocked out power to roughly 1.2 million customers across eight states. Entergy reported that Ida damaged 30,000 utility poles — nearly as many as Katrina and Hurricane Laura combined.

Ninety percent of Louisiana customers had power within two weeks, but the hardest-hit parishes along the coast — Lafourche, Terrebonne, and lower Jefferson — required a near-complete grid rebuild. Entergy’s official “no later than” date for full restoration was September 29, 31 days after landfall. Grand Isle, a barrier island community, waited even longer. Thousands of customers whose homes were too damaged to accept power were excluded from restoration counts entirely.

5. Hurricane Michael — 27 Days (2018)

Michael hit the Florida Panhandle on October 10, 2018, with 155 mph winds — just 2 mph short of Category 5 at the time (it was later reclassified). Mexico Beach was nearly leveled. Across Bay, Calhoun, and Jackson counties, the electrical infrastructure required a complete rebuild, not a repair.

Gulf Power restored 95% of customers who could safely take power within 13 days. But in Mexico Beach and rural inland counties, the grid had to be built from scratch. On November 6, 27 days after landfall, Governor Rick Scott confirmed that power had been restored to all customers capable of receiving it. In Jackson County, officials estimated 50–60% of homes were damaged or destroyed.

6. North Country Ice Storm — 23 Days (1998)

The longest non-hurricane outage in U.S. mainland history struck upstate New York in January 1998. Nearly four days of continuous freezing rain coated power lines and trees in inches of ice across Jefferson, St. Lawrence, Franklin, Clinton, and Essex counties. Only 8,000 of 110,000 electric customers had power immediately after the storm.

The final customers waited 23 days. Nine people died — from carbon monoxide poisoning, falls, fire, and hypothermia. The American Red Cross operated 80 emergency shelters. A year later, the Post-Standard called it “arguably New York’s storm of the century” in terms of costs ($365 million), poles destroyed (8,000), and duration.

This event is the closest non-hurricane comparison to what Gary experienced: a prolonged outage in a defined geographic area, driven not by flooding that prevented access but by sheer infrastructure destruction.

7. Hurricane Irma — 20 Days (2017)

Irma made a direct hit on the lower Florida Keys on September 10, 2017, as a Category 4 hurricane with sustained winds exceeding 120 mph. All 30,000 Keys Energy Services customers lost power. Initial assessments suggested restoration could take months.

Instead, Keys Energy re-energized the last homes that could accept power 20 days after the storm — a result the utility credited to years of storm-hardening its poles to withstand Category 5 winds. The Florida Keys Electric Cooperative, serving the upper and middle Keys, restored all capable members by September 23, 13 days after the storm. On the mainland, FPL had 95% of its 5 million customers back within eight days.

8. Iowa Derecho — 16 Days (2020)

The August 10, 2020, derecho is the most direct precedent for Gary. Winds exceeding 140 mph tore through Iowa, knocking down an estimated seven million trees across the state. Cedar Rapids, a city of 137,000, experienced a near-complete blackout. Every traffic signal in the city was damaged. Alliant Energy had to replace 3,600 poles and install six million feet of wire.

Most Cedar Rapids residents had power within one to two weeks. The last 500 customers were restored 16 days after the storm. At least two families went 15 days in the dark. The 2020 derecho caused $11 billion in damage, making it the costliest thunderstorm in U.S. history at the time.

The parallels to Gary are striking: both were derechos, both hit mid-sized cities with aging infrastructure, and both saw the utility struggle to explain the pace of restoration to residents.

9. Superstorm Sandy — 14 Days (2012)

Sandy’s surge flooded subway tunnels in Manhattan and destroyed beachfront communities across the New York metropolitan area. The Rockaways peninsula and parts of Staten Island waited two full weeks for power. The combination of saltwater damage to underground and coastal infrastructure, plus the sheer density of the affected area, made restoration exceptionally complex.

10. Gary, Indiana Derecho — 14 Days (2026)

The August 11, 2026, derecho hit Gary with 99 mph winds, knocking out power to over 301,000 NIPSCO customers across northwest Indiana — the largest outage in the utility’s history. Two weeks later, an estimated 5,000 homes remained without power, nearly all in Gary.

NIPSCO reported that 300 distribution poles and 44 high-voltage transmission poles needed replacement in Gary alone. Subsequent thunderstorms on August 20 re-knocked power to thousands who had just been restored, compounding the crisis.

The outage drew national attention in part because of its equity dimensions. Gary is a predominantly Black city where roughly one in three residents lives below the poverty line. Mayor Eddie Melton publicly challenged NIPSCO’s pace: “Twelve days is too long for families to be without power.” Governor Mike Braun requested FEMA disaster relief and asked the state utility commission to investigate NIPSCO’s response.

NIPSCO estimated full restoration by the end of August 25 — exactly 14 days after the storm.

How Common Are 14-Day Outages?

Fourteen days is rare but not unprecedented. Outages of two weeks or more have occurred roughly once every one to two years over the past two decades. They share a consistent pattern:

• Cause: Hurricanes dominate the top of the list, but ice storms and derechos cause outages just as long. Both snap poles and bring down trees over wide areas, requiring pole-by-pole, span-by-span reconstruction rather than switching on backup feeds. The distinction is that hurricanes get federal attention; ice storms and derechos often don’t.
• Geography: Areas with heavy tree cover, older infrastructure, and fewer redundant circuits. Rural electric cooperatives and smaller municipal utilities appear disproportionately in extended outages.
• Compounding weather: In at least four of the events above, secondary storms struck during restoration, re-knocking power to customers who had just been reconnected. This happened in Gary when storms hit on August 20.
• Poverty and infrastructure age: Communities with older grids and less investment in vegetation management tend to experience longer outages. The equity dimension is not incidental — it’s structural.

Why Duration Matters More Than Scale

The 2003 Northeast Blackout affected 55 million people but lasted less than four days. Hurricane Maria affected 3.4 million people but lasted nearly a year. In terms of human suffering, economic damage, and loss of life, duration is the more important variable.

After 72 hours without power, the situation escalates rapidly:

Gary’s 14-day mark is the threshold where an outage crosses from “severe weather event” into a story about infrastructure, investment, and equity.

What Happens After the Lights Come Back On

Every extended outage in this list triggered the same cycle:

1. Investigation. State regulators review the utility’s storm response, vegetation management practices, and mutual-aid agreements. Indiana’s governor has already asked the state utility commission to investigate NIPSCO.
2. Investment. Utilities accelerate grid-hardening programs: undergrounding lines, replacing wooden poles with composite or steel, improving sectionalizing so faults don’t cascade.
3. Rate cases. The cost of those investments gets passed to ratepayers, often sparking a second round of public frustration.
4. Policy changes. After the 2020 Iowa derecho, Alliant Energy invested in a grid resilience program. After Winter Storm Uri in Texas, the legislature mandated weatherization for power plants. After Maria, Puerto Rico began a long transition toward solar microgrids.

Whether Gary’s outage produces lasting change or fades from the news cycle will depend on the same factors it always does: political will, regulatory follow-through, and how much capital NIPSCO and its ratepayers are willing to invest in a grid that can survive the next derecho.