The Rockefeller Center Christmas Tree has been a New York tradition since 1933 (when the 30 Rock Plaza opened and arboreal bloodlust was in the air), but the first tree actually went up in 1931, while the site was still under construction.
The very first tree you see here was put up and decorated by construction workers. It stood 20-feet high, and according to Daniel Okrent, in Great Fortune: The Epic of Rockefeller Center, it was adorned with "strings of cranberries, garlands of paper, and even a few tin cans" by Christmas Eve of that year. Okrent also notes that while the men, who by this time were bearing the brunt of the Great Depression, "didn’t look fortunate... each was handed proof of his luck: a paycheck" at the wooden crate you see beside the tree.
This year's tree will be up until January 7th, and is way more showy than the its humble ancestor.