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Natural Disasters: Economic Effects of Hurricanes Katrina, Sandy, Harvey, and Irma

GAO-20-633R Published: Sep 10, 2020. Publicly Released: Sep 10, 2020.
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Fast Facts

Katrina, Sandy, Harvey, and Irma—4 of the costliest hurricanes in the U.S. since 2005—caused damage totaling trillions of dollars. Their effects on economic activity and employment in damaged areas varied widely. State and local government officials said that the storms significantly affected certain communities, local governments, households, and businesses.

Communities are taking actions to improve resilience (e.g., elevating homes, erecting flood barriers), but many remain vulnerable. Factors like availability of funds and analysis of costs vs. benefits affect communities' decisions about what to improve and how to do it.

Mitigation projects, like this system of levees and other barriers in New Orleans, could improve communities' resilience to coastal storms and flooding.

Aerial view of a levee spanning a waterway, with an opening in the center.

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Why GAO Did This Study

Between January 1980 and July 2020, the United States experienced 273 climate and weather disasters causing more than $1 billion in damages each, according to NOAA. The total cost of damages from these disasters exceeded $1.79 trillion, with hurricanes and tropical storms accounting for over 50 percent of these damages, according to NOAA. Across the regions affected by these hurricanes over the period from 2005 to 2015, CBO estimated that federal disaster assistance covered, on average, 62 percent of the damage costs. GAO has reported that the rising number of natural disasters and reliance on federal disaster assistance is a key source of federal fiscal exposure.

GAO was asked to review the costs of natural disasters and their effects on communities. This report examines (1) estimates of the costs of damages caused by hurricanes and hurricanes' effects on overall economic activity and employment in the areas they affected, and (2) actions subsequently taken in those areas to improve resilience to future natural disasters. GAO conducted case studies of Hurricanes Katrina, Sandy, Harvey, and Irma, selected for two reasons. First, they were declared a major disaster by the President under the Robert T. Stafford Disaster Relief and Emergency Assistance Act, which establishes key programs through which the federal government provides disaster assistance, primarily through FEMA. Second, they had sizable effects on the 50 U.S. states and the District of Columbia during the period from 2004 through 2018. GAO analyzed federal agency and other data on costs, economic activity, employment, and recovery and mitigation projects in selected areas affected by these hurricanes. GAO also visited selected recovery and mitigation project sites; interviewed experts and federal, state, and local government officials; and reviewed federal, state, and local government reports and academic studies.

What GAO Found

Hurricanes Katrina, Sandy, Harvey, and Irma (selected hurricanes) caused costly damages and challenges for some populations in affected communities. In these communities, the National Oceanic and Atmospheric Administration (NOAA) estimated the cost of damages to be approximately $170 billion for Katrina, $74 billion for Sandy, $131 billion for Harvey, and $52 billion for Irma. These estimates include the value of damages to residential, commercial, and government or municipal buildings; material assets within the buildings; business interruption; vehicles and boats; offshore energy platforms; public infrastructure; and agricultural assets. These hurricanes were also costly to the federal government. For example, in 2016, the Congressional Budget Office (CBO) estimated that federal spending exceeded $110 billion in response to Katrina and $53 billion in response to Sandy.

GAO analysis suggests that the selected hurricanes were associated with widely varying effects on overall economic activity and total employment in affected metropolitan areas and counties. Economic activity was lower than expected in the month of the hurricane or some of the three subsequent months in three of the affected metropolitan areas GAO analyzed. Within one year, average economic activity in these three metropolitan areas was similar to or greater than what it had been the year before the hurricane. Total employment was lower than expected in the month of the hurricane or some of the three subsequent months in 80 of the affected counties GAO analyzed. Total employment was higher than pre-hurricane employment on average in 47 of those counties within one year but remained below pre-hurricane employment on average in the other 33 counties for at least one year. Finally, state and local government officials said that the selected hurricanes had significant impacts on communities, local governments, households, and businesses with fewer resources and less expertise, and that challenges faced by households may have impacted local businesses.

Communities affected by selected hurricanes have been taking actions to improve resilience, but multiple factors can affect their decisions. Actions taken after selected hurricanes include elevating, acquiring, and rehabilitating homes; flood-proofing public buildings; repairing and upgrading critical infrastructure; constructing flood barriers; and updating building codes. A community’s decision to take resilience actions can depend on the costs and benefits of those actions to the community. Multiple factors affect these costs and benefits, including the likelihood, severity, and location of future disasters, as well as the amount of federal assistance available after a disaster.

Finally, vulnerabilities remain in areas affected by selected hurricanes. For example, state and local government officials indicated that many older homes in these areas do not meet current building codes. In reports to the Federal Emergency Management Agency (FEMA), states indicate they anticipate that the scope of damages via exposure to weather hazards, such as hurricanes, will likely remain high and could expand across regions affected by the selected hurricanes. In addition, some local governments have projected that population will grow in the regions affected by selected hurricanes.

For more information, contact Oliver Richard at 202-512-8424 or

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