Gatsby Riddle... can you guess it...?

The paragraph below is most unusual. How quickly can you find out what is so unusual about it? It looks so ordinary you'd think nothing was wrong with it - and in fact, nothing is wrong with it. It is unusual though. Why?

"Gatsby was walking back from a visit down in Branton Hill's manufacturing district on a Saturday night. A busy day's traffic had had its noisy run; and with not many folks in sight, His Honour got along without having to stop to grasp a hand, or talk; for a mayor out of City Hall is a shining mark for any politician. And so, coming to Broadway, a booming bass drum and sounds of singing, told of a small Salvation Army unit carrying on amidst Broadway's night shopping crowds. Gatsby , walking towards that group, saw a youg girl, back toward him, just finishing a long, soulful oration ... "

The above passage is taken from the book "Gatsby" written by Ernest Vincent Wright in the late 1930's