This section is from the book "Practical Real Estate Methods For Broker, Operator & Owner", by Thirty Experts. Also available from Amazon: Practical Real Estate Methods for Broker, Operator, Owner.
When it came to a section like Harlem, 125th Street very early stood out as the coming main street of a country town of 300,000 to 500,000 people, and it required no great foresight to conceive the march of the now famous Harlem with its local pride, having social clubs, churches, places of amusements, etc. The more fun that was poked at these little Harlem flats, the more popular they became. They received lots of free advertising in the newspapers and on the stage.
After Harlem was pretty densely populated, you had to turn to the Bronx, and again one could foresee that the woodworking establishments and breweries and other factories offering employment to thousands, would draw a larger population, and that lots selling at $1,000 apiece and acres at $3,000 to $4,000 had to increase largely in value. Here was a desirable neighborhood selling below its value. See the result. Lots in Third Avenue in the neighborhood of 149th Street, now selling at $50,000 and over, then sold at $5,000.