It´s a typical traffic in New-York City: very busy and mostly taxi cabs. The taxicabs of New York City, with their distinctive yellow paint, are a widely recognized icon of the city. There are more than 13,000 taxis operating in the city, not including over 40,000 other for-hire vehicles. Taxicabs are operated by private companies.

Sources, related links:
Wikipedia - Taxicabs of the United States
The New York City Taxi and Limousine Commission (TLC)