
There was no organized program to manage and protect United States' forests before 1875. No organization existed to champion fledgling forestry efforts being developed to save and manage American forests. There was no government over-site for vast stretches of American trees and no fire protection. Not one professional forester was trained in the United States.
All that was about to change.
Forestry became an American profession at the end of the 19th Century and was first taught at Cornell University and Yale. These universities created the first college level forestry schools in the Western Hemisphere. University-taught foresters were primarily employed in the newly created United States Division of Forestry, later to be called the United States Forest Service.
A massive conservation movement took the Nation by storm and was instrumental in the creation of the first Timberland Reserve which later became know as Yellowstone National Park. Millions of acres of forest land were later purchased to make up one of the largest public forest ownerships in the World - our National Forests. We still enjoy these forests today...
Yellowstone Timber Reserve - National Park Service Illustration

Most well-established trees can tolerate some drought. Much depends on the drought resistance of certain species and whether they are growing on an appropriate site.
Moisture sensitive tree species like dogwoods, Japanese maples, flowering cherries, and birches may need extra water in times of drought. Oaks, red maples, tulip poplars, sycamores, crabapples, hawthorns, elms, gingkos, and hackberries are noted for their drought resistance so should be a preferred species to plant in drought-prone areas.
Japanese Maple Leaf Scorch - Steve Nix Photo, Licensed to About.com
Nearly every state and province has a forestry association that represents forestry practiced by both the forest owner and forestry trade organizations. These forestry associations are designed to protect timber growers and timber processors from excessive regulation, provide them with continuing education in the effort to grow and harvest trees and recognize excellent forest stewardship. Here are many of the largest forestry associations in North America. Let me know if I missed your favorite!
A United States Forest Service report called the
Check List of Native and Naturalized Trees suggests that there may be more than 865 different species of trees in the United States. Here are the 10 most common native tree species in the United States, based on several Federal surveys of tree stem count, and are listed with the most common first: