John McFadden no longer sticks his hand out for a yellow cab. He has plenty of other options at his fingertips.

With a couple of taps on his phone, he lines up rides with Via, a car-pooling service that shuttles him around Manhattan with strangers for a flat rate of $5. When he wants to ride alone, he taps again, this time summoning a car through Uber.

“I used to go out and hail a cab, but this is more convenient,” said Mr. McFadden, 47, a photographer. “We all use our phones all day, every day.”

The yellow cab may be as synonymous with New York as pizza, Broadway and the Empire State Building, but more and more it is no longer the ride of choice. This fixture of city life — a touchstone of popular culture in movies like “Taxi Driver’’ and the hit television series “Taxi” — was once the main alternative to subways and buses, hailed by rich and poor alike. Cabdrivers were the ambassadors of the streets, welcoming newcomers, passing along city lore and dispensing advice even when no one asked.