top of page

About The Impact Census 



The Impact Census is a tool to help communities assess the real costs of flooding they are experiencing. Created and directed by two economists, the Census partners with flood-impacted communities to survey their losses, providing pro bono survey design, implementation, and economic analysis for household flooding costs.  


The Impact Census can be used to help policymakers and individuals identify and understand flooding costs, and to learn about best practices and gaps in resilience efforts and funding. It also provides an important tool and resource for community leaders, researchers, and advocates working to address chronic flooding impacts.  


The Impact Census is not a census in the formal definition of survey analysis, which surveys every entity to which the subject of the survey applies. The Impact Census’s approach is to draw a random sample of impacted households to estimate the overall impact on a community, beginning with a small sample of 50 to 100 respondents. The Census then refines the survey to fit a community’s specific needs and circumstances and conducts a larger random sample from the entire population. 




While many communities around the country are increasingly affected by chronic flooding, there is no accurate information on the impact of chronic flooding to American households. Government and insurance data include insurance reimbursements from flooding events and limited disaster relief support, but exclude high deductibles, uninsured losses, and many other costs, such as missed work and health impacts.


The result is a systematic underestimation of flooding costs to households, and policies that consistently fail to address problems faced by the communities, or even make them worse. Without a clear picture of the real costs of flooding, it is harder to promote investments that will reduce future impacts, and easier to justify development policies that make flooding impacts worse for surrounding communities.


The Impact Census aims to address these data gaps by surveying uninsured costs and other personal losses that may be related to flooding. For individuals, these costs can include but are not limited to lost work, under or uninsured health care costs, debt, and property damages. The Impact Census is recording these costs to increase public awareness and enhance the ability of municipalities to understand, manage, communicate, and adapt to the changes they are experiencing.





Horry County is a coastal community in the northeastern coastal plain of South Carolina. Located along the Atlantic Ocean, more than 50% of the incorporated county includes wetlands, marshes, and other water features. Horry County is also the largest county in South Carolina and the second fastest growing municipality in the nation. More than 35,000 people have moved to the county over the past two years and conservative estimates of population growth predict 275,000 new residents by 2040. 

The growing population of Horry County has lead to an increase in development and urbanization. However, the current county codes, ordinances, and infrastructure were not designed to accommodate the current pace of population growth, increase in land use changes due to development, and changes in weather patterns. Since 1996 the county has seen a 22% increase in impervious cover, and loss of forested and wetland area, reducing natural absorption of floodwaters. With about 24% of the county located within the 100-year floodplain, continued development and urbanization have contributed to an increase in flooding impacts due to an increase in rainfall and severe storms.


Compounding the effects of urban flooding, Horry County has also experienced 3 catastrophic flooding events as a result of Tropical Storm Joaquin, Hurricane Matthew and Hurricane Florence. Residents of Horry County are vulnerable to storm surge, riverine and flash flooding.


Horry County Rising has been advocating for the county to have a plan to improve flood resilience, including discouraging development of the floodplain and working to improve their CRS (community rating system) score for the National Flood Insurance Program. Horry County Rising is a grassroots movement by the people of Horry County to help affected families mitigate their flood risk and vulnerability through education, empowerment, and engagement. The survey data and analysis conducted by the Impact Census will help Horry County Rising and affected families rebound quicker after a major flood and prevent catastrophic economic losses. 


The data will prove the need to invest in smart infrastructure and reorient the county’s investment focus to projects that remove assets from the floodplain, increase water storage, expand conveyance systems, and prevent wetland losses to preserve natural infrastructure. The project will also help future proof our county by implementing and enforcing flood mitigation on all future land use projects. Propelling low-impact development principles and requiring engineering and construction of new projects that are adaptable to high water and peak rainfall will lead to a more resilient community. You can read more about Horry County’s work at




The Impact Census collects data in collaboration with local community advocates and engaged citizens to ensure that they retain individual control over the use and publication of their data. No published information will personally identify individuals. If you have any questions, please contact us at


Dr. Laurie Johnson directs the Impact Census. Prior to the Census, Laurie was the chief economist at the Natural Resources Defense Council’s (NRDC) clean air program for seven years, and before that a professor of economics at the University of Denver for eight years. During her academic career, Laurie taught cost benefit analysis, statistics, macroeconomics, microeconomics, environmental economics, experimental economics, and poverty. She then worked at the NRDC to identify best practices in government modeling of environmental regulatory costs and benefits. Laurie has developed original interdisciplinary surveys, as well as economic experiments and games, that have been published in top journals, including the Journal of Risk and Uncertainty, the Journal of Economic Behavior and Organization, and Ecological Economics. She received her Ph.D. in economics from the University of Washington, Seattle. She is an instructor in environmental economics at the University of Massachusetts, Amherst, and is an affiliated scholar with the New York University’s Institute for Policy Integrity.

bottom of page