The most important use of a city directory is to
place a city- or town-dwelling ancestor at a specific place at a single point in
time. Census records can help you here every ten years, and some state censuses can
help for that in-between period. But city directories may help you fill in the gaps.
This is especially true in the critical period between 1880 and 1900 when the 1890
census was almost completely destroyed by fire.
These city directories were typically published each year. Since they were intended for use for such a short period, they were seldom printed on anything other than cheap paper. This is unfortunate because many directories have crumbled and, in many cases, no copies survive. A city or town's collection may be woefully incomplete because no one perceived the value of preservation at the time.