By now, most people recognize that flooding across the U.S. is happening more often, and causing greater damage. While some regions seem to flood year after year, others may only face major flood events once in a generation. So why the difference between flood states?
Understanding where floods happen most often and why can help protect homes, businesses, and critical infrastructure. Below, we break down what makes certain states more flood-prone and what property owners can do to reduce their risk.
What Makes a State More Prone to Flooding?
Flood risk isn’t caused by one single factor. It’s typically the result of several conditions working together:
- Geography and elevation - Low-lying areas and regions with flat terrain are more susceptible to flooding because water has fewer natural pathways to drain away.
- Proximity to oceans, rivers, and floodplains - Properties located near coastlines, rivers, or within floodplains face higher flood risk due to storm surge, river overflow, and rising water levels.
- Weather patterns and storm frequency - Regions that experience frequent heavy rainfall, hurricanes, or intense storms are more likely to see repeated flooding events.
- Urban development and drainage capacity - Dense development and impervious surfaces overwhelm stormwater systems, causing water to accumulate even during moderate rainstorms.
- Soil type and land absorption ability - Certain soil types absorb water poorly, increasing runoff and limiting the ground’s ability to naturally manage excess rainfall.
Flood states check multiple boxes on this list, which is why they tend to experience flooding more frequently and with greater severity.
Examples of High-Risk Flood States
Coastal States: Storm Surge & Sea Level Rise
Examples: Florida, Louisiana, Texas, the Carolinas, New Jersey
Coastal flood states face risks from multiple scenarios, including hurricanes, tropical storms, nor’easters, and even routine high tides. These types of weather events push seawater inland, overwhelming drainage systems and low-lying neighborhoods.
Key risk factors include:
- Storm surge from hurricanes
- Rising sea levels increasing baseline flood risk
- Flat terrain that allows water to spread quickly
- Saltwater intrusion damaging electrical and mechanical systems
In many coastal cities, flooding is no longer limited to major storms - sunny-day flooding is becoming more common. Sunny-day flooding occurs when high tides push seawater inland, causing flooding even without rain or storms, especially in low-lying coastal areas. As sea levels rise, these events are becoming more frequent and can damage infrastructure, disrupt daily life, and increase long-term repair costs.
River & Floodplain States: Inland Flooding Events
Examples: Missouri, Iowa, Illinois, Ohio, Mississippi
States along major river systems face flooding driven by prolonged rainfall, snowmelt, and upstream water release. When rivers exceed capacity, water spreads across floodplains, often impacting communities far from any coastline.
Common causes include:
- Heavy rainfall over large drainage basins
- Spring snowmelt combined with rain
- Aging levees or overwhelmed river controls
- Development within historic floodplains
These floods can last days or even weeks, causing extended business and infrastructure disruptions.
Mountain & Western States: Flash Flooding
Examples: Colorado, Utah, Arizona, Washington, Oregon, California,
Flooding in western and mountainous states often happens quickly and with little warning. Steep terrain prevents water from soaking into the ground, sending it rushing downhill into cities, canyons, and desert communities.
Contributing factors include:
- Burn scars from wildfires reducing soil absorption
- Slow-moving atmospheric rivers
- Sudden, intense rainfall events
- Narrow canyons and urban runoff channels
- Drought-hardened soil that repels water
Flash floods are especially dangerous because they develop rapidly and leave little time to deploy emergency protections.
Urban States: Infrastructure Overload
Examples: New York, New Jersey, Massachusetts, Illinois
Highly urbanized states experience flooding even without extreme weather. Impervious surfaces like roads, sidewalks, and parking lots prevent water from absorbing into the ground, overwhelming stormwater systems.
Urban flooding is often caused by:
- Aging or undersized drainage infrastructure
- Increased development density
- Basement and underground space vulnerability
- Limited space for water to disperse naturally
This type of flooding can occur during moderate rain events, not just major storms.
Why Flooding Is Becoming More Frequent Everywhere
Many property owners assume flood risk only applies if they’re in a FEMA-designated flood zone, near a river or coastline, or in a hurricane-prone state. In reality, over 25% of flood insurance claims come from properties outside high-risk flood states.
Even states that historically had low flood risk are now experiencing more frequent flood events due to:
- More intense rainfall in shorter periods
- Rising sea levels increasing coastal flood reach
- Urban expansion reducing natural drainage
- Aging infrastructure not designed for today’s climate realities
All of the above points to the reality that flooding is no longer a “coastal-only” problem. As flooding has become a year-round issue across the United States with more inland flooding that isn’t a result of hurricanes or storm surge, the definition of ‘flood states’ begins to blur.
Key Takeaways
Flooding in the U.S. is increasing in both frequency and severity, driven by a combination of geographic, environmental, and human factors rather than a single cause. Flood states experience the most flooding because they often face multiple risk conditions at once, such as low elevation, proximity to water, intense weather patterns, dense development, and poor soil absorption, making them more vulnerable to repeated events.
Importantly, flooding is no longer limited to coastal or high-risk flood zones; inland, urban, and historically low-risk areas are now experiencing more frequent flooding due to changing weather patterns, expanding development, and aging infrastructure. Understanding these regional risks is critical for property owners and municipalities looking to reduce damage and plan effective flood protection strategies.
If you have property in one of the flood states or you’re unsure about your flood exposure, our team can help assess your risk and develop a plan tailored to your property. Contact our team of flood experts to get started.