GDP: The Brooklyn Bridge

Jul 30, 2013 • Demand, Supply, and Markets, Developing Economies, Economic Growth, Economic History, International Trade and Finance, Labor, Macroeconomic Measurement, Tech • 242 Views    No Comments

The story of the Brooklyn Bridge is really about cheap steel.

Used to iron that tended to be brittle, 19th century bridge builders had little experience with steel. And yet, the dimensions of the Brooklyn Bridge required what steel could provide– a breaking strength of 3400 pounds, something “neither too hard nor too soft” and 6.8 million pounds of wire that could lay straight on the floor “without any tendency to spring back into coils.

Only with steel could the Brooklyn Bridge became the longest suspension bridge in the world. 85 feet wide and 5862 feet long, it had to extend 1600 feet over the East River between Manhattan and Brooklyn and then gradually slope downward toward land on both sides. When planners told of the load it would support, they referred to carriages and farm wagons, to personal and commercial traffic, to a special bridge train and a pedestrian promenade. Doubters said it was impossible.

The Brooklyn Bridge was completed in 1883.

Cheap steel made the bridge feasible. When the price of steel plunged from $250 or $300 to $30 a ton and then continued to move lower because of Bessemer steel, the Brooklyn Bridge became affordable. The ferries that shuttled people and goods between Brooklyn and Manhattan had limited capacity and weather related inconsistency. By contrast, a bridge would bring merchants new customers, Brooklyn would get new residents, manufacturers could transport their goods with ease, workers could commute dependably and even the mail could be transported more easily.

And that takes us to the GDP. A yardstick of the value of goods and services produced during one year in the US, the GDP reflects a country’s affluence. A higher GDP usually means more jobs, rising incomes and an ascending standard of living.

Perhaps even more than cheap steel, the story of the Brooklyn Bridge is about how innovations become affordable, spread, and increase the GDP.

Sources and resources: Hat tip to John Steele Gordon. His column in Barron’s, “Making Steel Affordable” perfectly explained why “the world changes” when commodities like steel cost less. Moving from Gordon’s single page column to David McCulloch’s 608 page story of the Brooklyn Bridge, I found The Great Bridge the perfect way to see the struggles people experience when they suggest something new.

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