The words of "O Little Town of Bethlehem" are by Phillips Brooks(1835–1893), an Episcopal priest, then rector of Church of the Holy Trinity, Philadelphia and later of Trinity Church, Boston. He was inspired by visiting the village of Bethlehem in 1865. Three years later, he wrote the poem for his church, and his organist Lewis Redner (1831-1908) added the music. Redner's tune, simply titled "St. Louis", is the tune used most often for this carol in the United States. In Great Britain Vaughan Williams set the carol to the English traditional melody, "The Ploughboy’s Dream", which he re-titled "Forest Green" in 1903. It first appeared in the English Hymnal in 1906.
The first printing of the tune was a broadside titled "The Plow-boy's Dream", published by J. Marshall in London in 1795, now in the Bodleian library. I have included this tune because after singing these words to Redner's chromatic tune, I find "Forest Green" nicely straightforward and singable.