RAPID CITY, S.D. — South Dakota ranks as the fourth best state in the nation for surviving a zombie apocalypse, according to a new study released during Zombie Awareness Month by Canada Sports Betting.

The study analyzed all 50 U.S. states and 14 Canadian provinces using a composite index based on vulnerability, defense, resources and physicality. Wyoming claimed the top spot in the rankings, followed by Vermont and North Dakota.

South Dakota earned a survival probability of 6.41%, helped largely by what researchers called an extremely low vulnerability score.

South Dakota received a vulnerability score of just 0.43 out of 100, the second lowest in the entire study behind neighboring North Dakota. Researchers said the state’s low population density, minimal urbanization and limited public transit use would likely slow the spread of a fictional zombie outbreak.

The state also scored well in defense, earning a 55.85 rating based on firearms ownership, military bases and veteran populations. South Dakota’s resources score came in at 27.27, which researchers said reflected reasonable access to hardware stores, supplies and hospital capacity for a state of its size.

According to the study, the rankings were determined using weighted categories that included vulnerability at 20%, defense at 40%, resources at 20% and physicality at 20%. Physicality factors included obesity rates and average annual temperature. All metrics were scaled to a 0 to 100 range before being combined into a final survival index.

The full study and rankings are available from Canada Sports Betting.