The Marx Library has been a Federal Depository since 1968.
As required by the U.S. Constitution (Art. I, Sec. 2), the Census Bureau conducts a complete count of residents of the U.S. every ten years, ending in "0". Known as the Decennial Census, the primary purpose of this count is to determine the apportionment for representatives in Congress. The information that is compiled in the Census is obtained from questionnaires. Some basic information (e.g.: age, sex, race) was obtained from all residents (100% data), whereas other, more detailed questions (e.g.: income, education, employment status) were only asked of a portion of the population (sample data). Starting with the 2010 Census, sample data were no longer compiled from the decennial census but rather will be obtained through the annual American Community Survey.