In the beginning, New Yorkers utilized the Hudson River and the New York Bay for transportation. They had limited access to land and needed a way to generate more space without expanding to new lands. They built skyscrapers to make more building space and they dug underground tunnels to build railroads that later became what is now the subway system. In addition to New York’s space saving on land they also had different bridges to make entering and leaving the city easier. Out of the eight bridges that enter and leave the city, Manhattan Queensboro Bridge is used the most, spanning across the East River. The city also uses underwater bridges, one being the Brooklyn Battery Tunnel, connecting the Borough of Brooklyn and the Borough of Manhattan.