If Americans think about bridges at all, it is typically in admiration of iconic bridges. The Golden Gate Bridge in San Francisco, the Brooklyn Bridge in New York City, and the Mackinac Bridge in northern Michigan fit the bill. Admired for their beauty, iconic stature, or sheer size, these bridges are backdrops for vacation selfies, the subject of paintings, and settings for movie and television scenes. Largely ignored are the workhorse bridges – particularly ubiquitous concrete bridges. Yet, if not for the concrete bridge, the mass adoption of the automobile and the extensive network of American highways might not have been possible.
It is concrete bridges omnipresence that allows them to go unnoticed. Concrete bridges are literally everywhere today. From small city park paths to interstates, the concrete bridge is more common than a Starbucks. They traverse small depressions, deep ravines, other roads, and rivers. Elevated highways erase the line between road and bridge often for great distances. The section of U.S. Highway One between Miami and Key West consists almost entirely of concrete bridges – for 113 miles.
American Bridge History
Modern America’s cornucopia of concrete bridges was not always the case. Few bridges existed prior to the nineteenth century. Railroads and cities were early builders of bridges. Railroads spanned gulfs first with wooden and later steel trusses. Steel suspension bridges, first developed in the early nineteenth century and largely built by cities, slowly grew longer and taller through the century. The iconic Brooklyn Bridge, when it made its debut in 1883, was the largest steel suspension bridge in the world.
Concrete bridges, common place now, had to wait until the twentieth century to dominate the landscape. The technology to build concrete bridges existed before the Civil War. Yet steel was the preferred material for most bridge construction prior to the twentieth century. Railroads could easily ship the steel components for bridges to construction sites; engineers preferred to design steel truss and suspension bridges; government officials and the public shared the belief that steel equaled strength.
Good Roads
Then people went plain nuts for bicycles. Beginning in the 1890s, cycling became the preferred commuting method and go-to sport for urban Americans coast-to-coast. Urban cyclists used their bicycles for improved mobility in the city, and to escape the city on the weekend. These weekend excursions brough millions of cyclists in contact with the dismal state of American roads outside the city.
Whereas most cities had paved roads actively maintained by a streets department, rural roads of the era were a Mad Max no-man’s-land. Leaving the city brought cyclists from paved, level city streets to glorified dirt cow-paths full of mud, ruts, and potholes. Many weekend excursions left cyclists covered in mud and hopping mad.
The response was the Good Roads Movement. This movement was a grass-roots movement of cyclist enthusiasts who began lobbying county and state governments for better roads. As the 1890s gave way to the twentieth century, automobile enthusiasts joined the cyclists as they faced similar problems with the poor condition of American roads.
The Federal Government Gets Involved in Road and Bridge Building
The bicycle craze faded, but enthusiasm for automobiles did not. Intense lobbying by Good Roads groups now dominated by automobile owners, and later nationally organized under the American Automobile Association in 1902, led to federal action on roads. First with the Federal Aid Highway Act of 1916 and later with the better funded Federal Aid Highway act of 1921, the federal government became heavily involved in road building.
These two pieces of legislation put federal funding behind road building, but also put federal standards for highway construction behind road building. Gone were the days of a county paying a farmer to drag a log behind his horse team to build a road. Instead, states had to form official highway departments, hire engineers, and submit their road plans to the federal government for approval to get funding. Since the public demand for roads was high, each state complied.
Highway Construction Cost an Issue
The huge demand for roads put a subsequent demand on funding. The 1916 highway bill allocated a one-time sum pf $75 million across the U.S. for road building. It was quickly spent. The 1921 highway bill allocated $75 million a year for road building. State plans for highways exceeded even the larger amount of funds available in the 1921 highway bill.
This created the need to reduce costs – particularly in the west where distances between towns were longer and the terrain more formidable. In many western states, ravines, gullies, arroyos, washes, and canyons peppered the landscape. Building expensive steel bridges across all these obstacles made western highways more expensive.
Concrete Bridges to the Rescue
Enter the concrete bridge. Cheap and easy to build, concrete bridges could be quickly built over obstacles in the terrain large and small – often using the sand surrounding the bridge site. Roads too expensive to build with steel bridges were now feasible with concrete bridges. Many western highways of the era were planned only as gravel roads. Numerous steel truss or suspension bridges would make these too costly. With cheap concrete bridges, lonely low-volume western highways became possible.
And then a funny thing happened on the way to the rise of the automobile in the twentieth century. Other highway departments across the country discovered that concrete bridges made their projects cheaper too – making more road projects possible everywhere.
Counterintuitively, automobiles entered American life without roads to drive on. Had this situation continued, the mass adoption of automobiles might never have happened. Without a cost saving technology like the concrete bridge, fewer roads would likely exist limiting the utility of the automobile for individual mobility. Automobile enthusiasts might still outnumber general automobile users.
Today, general automobile users dwarf the number of automobile enthusiasts. Most Americans do not know how their automobile works – they just use it. Similarly, few consider the material used to build the road or bridge they drive on. However, the next time you use your car, take a moment to consider the concrete bridge. It played an astonishingly significant role in the rise of automobiles in American life and making travel by car possible almost everywhere.