Jake Riis and I spent one Sunday from morning till night in the tenement districts, seeing for ourselves what had happened.

Whoever, whatever was behind all this, "he" had moved his area of operation from the waterfront side of the city to the tenement district farthest inland.

From here, he made frequent trips into New York City, writing and reporting particularly on its impoverished tenement districts.

He mainly focused on tenement districts and said that the cost was one cent per child per hour of play.

But in the late 19th century the tenement districts became hugely overpopulated by immigrants swarming on the stoops.

Each year, tens of thousands of immigrants moved into the oldest tenement districts, resulting in intolerable living conditions.

In the early 1900s, the Volunteers moved into tenement districts in New York and other large cities to care for people in poverty.

Others were erected in congested tenement districts, with later ones built farther uptown.

He's going to have a book published soon, about the tenement districts.