On December 4, thousands will gather around the Rockefeller Center Tree to witness the twinkling lights blink on, while millions more will crowd around television sets worldwide to see the event.The tree lights up midtown Manhattan and serves as a glowing beacon of the Christmas spirit. But its Depression-era birth turns out to be far more humble. On Christmas Eve in 1931, construction workers put up a tiny, 20-foot balsam fir on the meek and mucky site of what would soon become Rockefeller Center. They strung it with cranberries, paper, and even tin cans. Christmas lights went up two weeks later at the behest of a Rockefeller Center publicist. Sadly, the tree disappeared the following year. The first official tree emerged in 1933. Rising 50 feet tall into the gray winter sky, it stood in Rockefeller Plaza, where it would…