There are about a million acres of land devoted to growing Christmas trees in the United States -- each acre produces the daily oxygen requirements of 18 people.
The freshest tree you can buy is one picked from a field and cut in front of you. Once it's been cut, shake the tree to remove any dead needles lodged in the foliage and branches.
If you are buying a tree at a retail lot, evaluate the tree's freshness by testing how firmly the needles are attached to the branches: Lightly grasp a branch and gently pull it through your hand, or bounce the tree on the bottom of its trunk against the ground several times -- if the tree is fresh, very few green needles should come off.
The best Christmas trees in North America are known for their symmetry, needle retention, attractive foliage, and, in many cases, distinctive fragrances.