When speaking of the New York skyline, we really should pluralize it because there is more than one.

There is the Midtown skyline, where the Empire State Building stands tallest among buildings, and at the lower Manhattan skyline One World Trade Center reaches the highest for the clouds.

The trend in building sky high in post-9/11 New York is in residential developments that includes 432 Park Avenue, a luxury apartment complex in Midtown that is the tallest of its kind in the Western Hemisphere. An even taller residential tower is in the works for a site nearby it.

These and other residential skyscrapers are slowly starting to dominate airspace above Manhattan the way commercial office buildings, such as the ESB and Woolworth Building, did in decades past.

A case in point (and the subject of this photo blog): Riverside Park South. This developing skyline spans wall-like along the Hudson River, roughly between W. 61st Street and W. 72nd Street. It consists of about a dozen high rises that include four condominium towers called Trump Place.

Immediately south of this area, the former site of Pennsylvania Rail Road yards, a new crop of mixed-use residential buildings are on the rise that are part of a development known as Riverside Center.

While these structures don’t quite compare in height to their soaring counterparts in Midtown, their locale on the edge of the West Side has created a limited though distinct section of skyline along the river. How much higher and denser will this area develop? I’ll be watching.