Bridges can be exciting pieces of infrastructure that connect otherwise distant places. New York City's Manhattan Island is connected to the rest of the country by 21 bridges. On the opposite coast, Greater Seattle is home to four of the longest floating bridges in the world, and San Francisco's Golden Gate Bridge is considered a national icon. However, bridges can also cost billions to maintain, and governments are responsible for repairing, replacing, and preserving them.
There are more than 600,000 bridges across the United States, with a concentration of about 14.7 bridges per 100 miles of public roadway, according to the federal government. A national analysis found that South Dakota has the #46 highest concentration of bridges in the U.S., at 7.2 bridges per 100 miles of public road.
TruckInfo.net identified the counties in South Dakota with the most bridges, using data from the Bureau of Transportation Statistics. Bridge counts are for 2020, the latest year with county-level data available. The analysis also includes data on bridge conditions, which don't factor into the rankings. A bridge, under federal regulations, is defined as a vehicle-carrying span at least 20 feet long that passes over a lower area of terrain or an obstruction, such as a waterway, railroad track, or other road.
Most of these structures aren't of the awe-inspiring variety. Most commonly, bridges are present throughout interstate and highway systems, connecting major roadways and allowing major roads and city streets to cross each other without complicated intersections. They also carry even small roads over dips in the landscape, rivers, creeks, and brooks. American motorists pass over bridges about 5 billion times per day, largely without a second thought.
Bridges are more concentrated in the Northeast, Midwest, and Southern regions of the U.S. The Northeast has the highest population density in the country, necessitating roadway bridges to allow a more concentrated populace to get from place to place. As the earliest region to be urbanized, the Northeast is also home to some of the oldest roadway bridges, some of which are crafted from stone.
Not all bridges benefit from that longevity. As of 2023, nearly 7% of bridges across the country are in poor condition, Federal Highway Administration data shows. Those rates are much higher in some parts of the country: In West Virginia, for example, nearly 1 in 5 bridges are in poor condition.
Repairs can be costly: Rebuilding the Bay Bridge connecting San Francisco and Oakland ended with a $6.5 billion price tag by the time the new and improved bridge opened in 2013. An American Road and Transportation Builders Association analysis found that about 1 in 3 U.S. bridges need to be replaced or repaired in some way, with a total estimated cost of $319 billion to complete them all.
Despite their challenges, the U.S. public roadway system couldn't function without its myriad bridges. Read on to see which South Dakota counties' roadways are most dependent on bridges.
