In 1810, about 3,000 people lived in Brooklyn, New York.
By 1850, more than 100,000 people lived there. To get to the island of Manhattan, they had to take a ferry across the East River. But the river often froze during the winter. Also, ferries were very crowded at rush hour. A new way of crossing was needed. In 1867, former Brooklyn Mayor Henry Cruse Murphy said a bridge would be a good idea. Two years later, construction began. It was to be one of the most amazing works of engineering ever.