Napa Valley gets struck by the largest earthquake in 25 years. Hurricanes churn through the Atlantic. Floods claim four lives as they sweep through parts of the Northeast. Every region in America faces its own dangers (those three are just from August), but when you account for all kinds of natural disasters–from earthquakes to winter storms to tornados–what place is safest of them all?

The honor goes to Sweet Grass County, Montana, according to an analysis of more than a half century of weather patterns and destructive natural events across the contiguous United States. Sweet Grass is home to 3,000 people who are fortunate enough to live far from wildfires to the west and twister country to the east, not to mention 900 miles from any trouble caused by the sea.

The same analysis ranks Ocean County, New Jersey, as the country’s most dangerous county, when it comes to frequency of natural disasters. Jersey Shore communities in Ocean County are vulnerable to tidal surges and storms like Sandy.

Here are the top 15 safest and most dangerous counties as measured by our “disaster index” (more on that below). Use the map above to see where your county ranks.

Safest Counties

The disaster index is calculated from all records in the National Oceanic and Atmospheric Administration storm events database, which includes earthquakes and tornados from 1950 and 42 other event types since 1996.

RANK COUNTY STATE DISASTER INDEX 2010 POP.
1 Sweet Grass County MT 1.7 3,651
2 Washington County ID 1.7 10,198
3 Wheatland County MT 1.8 2,168
4 Sherman County OR 2.0 1,765
5 Emporia city VA 2.0 5,927
6 Fergus County MT 2.3 11,586
7 Luna County NM 2.4 25,095
8 Liberty County MT 2.4 2,339
9 Grant County NM 2.5 29,514
10 Malheur County OR 2.7 31,313
11 Potter County SD 2.7 2,329
12 Hill County MT 2.8 16,096
13 Silver Bow County MT 2.8 34,200
14 Canyon County ID 2.8 188,923
15 Golden Valley County MT 2.9 884

 

Most Dangerous Counties

RANK COUNTY STATE DISASTER INDEX 2010 POP.
1 Ocean County NJ 223.7 576,567
2 Orange County CA 180.8 3,010,232
3 Cape May County NJ 174.3 97,265
4 Monmouth County NJ 173.8 630,380
5 Los Angeles County CA 171.0 9,818,605
6 Clinton County NY 156.8 82,128
7 Burlington County NJ 156.5 448,734
8 San Diego County CA 155.8 3,095,313
9 Franklin County NY 152.6 51,599
10 Riverside County CA 145.7 2,189,641
11 San Bernardino County CA 145.4 2,035,210
12 Atlantic County NJ 143.5 274,549
13 Chittenden County VT 143.3 156,545
14 Grand Isle County VT 142.3 6,970
15 Camden County NJ 139.3 513,657

 

Here’s how these places earned their rankings: The National Oceanic and Atmospheric Administration (NOAA) storm events database keeps track of forty-four different damage-causing natural phenomena. For earthquakes and tornados, its records go back to 1950, while all others events date back to 1996.

We tallied up every event in the contiguous United States that has caused death, property damage, injuries or crop damage in each county. Then we created a metric, called the disaster index, that is based on the average of each county’s events plus the events of its neighboring counties. A low disaster index means fewer events like dangerous storms. For example, California’s Orange County’s disaster index is the sum of its events (120) and all its neighbors events (754) divided by the count of neighboring counties plus one (5). This gives Orange County a safety index of 174.8.

When two counties have the same disaster index number, fatalities recorded by NOAA since 1950 in counties and neighboring counties are considered as part of the ranking.

All events are not equally dangerous. Hurricanes have claimed over a thousand lives in the U.S. since 1996 while wildfires have taken 99 lives during the same period. That said, counties that have very few of any of the 44 events tracked by NOAA are likely to be safest in the land, while many of those that have seen hundreds of incidents over the years are in places like hurricane-damaged New Jersey and earthquake-prone California.

Events measured by NOAA’s research include earthquake, hurricane (typhoon), cold wind chill, astronomical low tide, coastal flood, avalanche, dense fog, drought, dust devil, dust storm, excessive heat, extreme cold/wind chill, flash flood, flood, freezing fog, funnel cloud, hail, heat, heavy rain, heavy snow, high surf, high wind, ice storm, lakeshore flood, landslide, lightning, rip current, seiche, sleet, storm surge/tide, strong wind, thunderstorm wind, tornado, tropical depression, tropical storm, tsunami, waterspout, wildfire, winter storm and winter weather. You can use the drop down menu in the article’s headline to see how 3,114 counties rank in safety from each of those 44 different events.

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