The collection includes Frederick City directories as far back as 1859, the Hill-Donnelly Cross Reference Directory (1972 to present), and Frederick telephone books from 1920 to the present. Please note that in the nineteenth and early twentieth century Frederick had very erratic city directory coverage. The earliest know years of coverage are 1859, 1887, 1892, 1906, 1909, 1915, 1923-24, and 1928-29. During the 1930s, 1940s, and 1950s Polk published Frederick directories every two - three years. Beginning in 1962 directories were published yearly.