When the Queensboro Bridge opened for business on March 30, 1909, it cost three cents to ride over it on horseback and ten cents by car.

Ah, how times have changed. The days of the horse-drawn carriage and early automobile are long gone, but the original bridge, which turned 100 this week, is still going strong. In fact, said Sam Schwartz, president of the New York City Bridge Centennial Commission, thanks to repairs and renovations, the Queensboro Bridge is structurally sounder than it has been at anytime since World War II, if not earlier.

"After 20 years of reconstruction the bridge is stronger than it’s been in 50, even 75 years," said Schwartz, the former New York City Traffic Commissioner who presided over the bridge's modern remaking. "If we take care of the bridge going forward it will certainly last another 100 years."

The idea for the Queensboro Bridge was first conceived in 1838, but various obstacles delayed the start of construction on the project until 1902. At the time of its opening, the Brooklyn Bridge had already been built and the East River's other two suspension bridges, the Manhattan and Williamsburg Bridges, were under construction. Engineers for the Queensboro Bridge decided, however, that a cantilevered design would be cheaper and stronger than a suspension bridge.

Seven years later, when it opened to trolley and rail cars carrying commuters back and forth from Queens into Midtown Manhattan, then still a developing business district, the Queensboro Bridge with its unique design took its place among the city's most impressive architectural achievements.

The longest bridge spanning the East River, it quickly became a popular crossing point from Long Island City and Queens into Manhattan, and an important connector between the two boroughs.

"Queens became a bedroom community," said Schwartz. "Before the bridge was built it was harder to get [into] Manhattan."

Today, said Schwartz, the bridge is the most heavily used bridge within the city; 200,000 vehicles cross it every day. (The George Washington Bridge carries more daily traffic, said Schwartz, but falls in a separate category because it connects to another state).

To commemorate its history, the Bridge Centennial Commission will host a week-long series of events beginning May 31. To find out more, visit the New York City Bridge Centennial Commission's website at www.nycbridges100.org.