Nearly 7 million people on average use New York's Metropolitan Transit Authority bus and subway service each day.
New York Mayor Michael Bloomberg called the action "illegal and morally reprehensible" in a statement shortly after the strike was announced. Later the same day, state Justice Theodore Jones fined the Transport Workers Union $1 million a day for violating a state law that prohibits public employees from going on strike. The union plans to appeal.
Bloomberg put into effect the city's contingency plan outlined last week in case of a strike.
The plan includes requiring cars entering the city to have at least four passengers, delaying the start of New York City Public schools by two hours, suspending some on-street parking, and urging residents who normally rely on MTA bus and subway service to make alternate travel arrangements.
The contract between the Transit Workers Union and the MTA expired Dec. 15. The TWU extended its strike deadline until midnight Tuesday in hopes that an agreement would be found. Issues on the negotiating table included annual pay raise rates, an MTA proposal to raise the retirement age for new workers and health benefits.
TWU President Roger Toussaint said in a statement that the failed negotiations are particularly disappointing given MTA's $1 billion surplus. "They knew there was no good economic reason for their hard line on this issue -- not with a billion dollar surplus," he said.
Many New Yorkers encountered 20 degree temperatures when walking, biking or waiting in carpool lines in order to get to work. In a show of solidarity, Bloomberg walked across the Brooklyn Bridge to get to his office in lower Manhattan.
The last citywide transit strike was in 1980. That strike lasted 11 days. Bloomberg has estimated that the current strike could cost the city as much as $400 million a day.