Personal Experiences During the Chicago Fire, 1871

The sidewalks, except in the South Side business district, where limestone flags predominated, were entirely of pine or hemlock planking and many of the streets were raised on wooden supports from four to ten feet above the natural surface to meet the street grades which had by that much been raised above the natural surface. It can be seen what added fuel to a general fire was made by such construction of sidewalks and street pavements. The raised portions of the streets were sustained by heavy stone retaining walls on each side.