There were approximately 79,000,000 acres of these trees and almost all were gone by 1900’s. This wood was the main building material for homes and factories. Most structures built after 1930’s were from second generation pine trees that do not produce the very tight growth rings associated with the first generation timber. Plus, that rich amber color takes years to achieve. Heart Pine is rich in resin and in strength. Here is a video that gives you more insight.