Currently, the 140 years of the available US Census takes up more than 12,500 rolls of microfilm (average cost for the set is $450,000), representing over 500 million Americans.
The 1930 Census and the 1930 Census Fact Sheet
The only searching at all that the Census Bureau will provide is an Age Search for a fee for censuses from 1910 to 1990, but only for the named person, their heirs or legal representatives.
See also the Census Bureau Genealogy FAQs
The New York State Library's Federal Census Records for NYS summarizes what's available there.
The 1790-1820 population schedules were nearly all handwritten; the Government started using printed schedules in 1830. With each census, the forms asked for additional information.
The 1790-1840 schedules furnish only the names of the free heads of family, not of other family members. These schedules totaled the number of other family members, without name, by free or slave status. Also, the sex and age categories that the schedules first used only for free whites from 1790 through 1810 eventually applied to other persons, and the age categories increased after 1790.
The 1850 census was the first to record each person's name, specific age, occupation of those over age 15, place of birth, and value of real estate. The slave schedules, however, name only the slave owner and indicate only if a slave was black or mulatto, and his or her sex and age.
The 1860 schedules were almost identical to those for 1850, but the 1860 census was the first to inquire about the value of each free person's personal estate.
The 1870 schedule asked if a person's father or mother were foreign born.
The 1880 schedule was the first to ask about the relationship of each individual to the head of the family, specifying what could only be assumed in earlier censuses. Moreover, the 1880 census was the first to inquire about the birthplace of each person's parents, including the country of those who were foreign born. The census gives the state or country of birth, not the city or county.
A fire destroyed many 1890 population and special schedules, and water used to extinguish the blaze damaged many more. As a result, the Government disposed of most schedules. The few remaining 1890 population schedules or fragments are indexed and primarily cover veterans and widows of veterans.
The 1900 census contains the most information of all the schedules released to date, and gives for each person: name; address; relationship to the head of the household; color or race; sex; month and year of birth; age at last birthday; marital status; if a wife is listed within the household, then the number of years married, number of children born of that marriage, and number of children living; places of birth of each individual and of the parents of each individual; citizenship; if the individual is foreign born, then the year of immigration and the number of years in the United States; the citizenship status of foreign born individuals over age 21....
The 1910 census schedules record the following information for each person: name; relationship to head of household; sex; color or race; age at last birthday; marital status; length of present marriage; if a mother, number of children and number of living children; place of birth; place of birth of parents; if foreign born, year of immigration and citizenship status; language spoken; occupation.....
The format and information in the 1920 census schedules closely resemble that of the 1910 census. The 1920 census, however, did not ask about service in the Union or Confederate army or navy. Questions about the number of children born and how long a couple had been married were also omitted.
The 1930 Census was released in April of 2002. Most of it is not indexed (although that may be picked up by commercial ventures) with the exception of some southern states (Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and portions of Kentucky and West Virginia) which were soundexed. It reflects 123 million people on 2,668 reels of microfilm and 1,591 reels of soundex.
See the Nara site for good instructions on "How to Start Your 1930 Census Research" and this RootsWeb Soundex Converter can help you determine the codes for individual family names.
The 1940-2000 censuses are only good to supply numerical data at present, due to the 72-year confidentiality requirement. Next census release will be 1940 in 2012.
Privately Printed Indexes
Privately printed indexes are available for most States or territories from
1790 through 1870 and for the 1890 special schedules. For each state or
territory, these indexes typically alphabetize surnames (last names) and then
given (first) names or other names and initials of heads of families and specify
the county, city, and possibly an MCD (see Census
Bureau Glossary).
The Soundex Coding System
The Soundex is a coded surname (last name) index based on the way a
surname sounds rather than the way it is spelled. Surnames that sound the same,
but are spelled differently, like SMITH and SMYTH, have the same code and are
filed together. The Soundex coding system was developed to find a surname even
though it may have been recorded under various spellings. Every Soundex code
consists of a letter and three numbers, such as W252. The letter is always the
first letter of the surname whether it is a consonant or a vowel. The numbers
are assigned to the remaining consonants of the surname according to the Soundex
guide. Genealogy Today's article Demystifying
the National Archives describes using Soundex in easy to follow terms.
Enumeration District Descriptions and Maps
An ED refers to the area assigned to a single census-taker. Because
of errors in names transcribed and because of variant uncommon spellings of a
name, the researcher may not be able to locate an entry in the Soundex system
for a given head of family or individual living in a specific area. Persons
wishing to consult the schedules for a given town, a minor civil division or
geographic area, or a ward of a large city need to know the enumeration district
numbers assigned to that designated place. ED descriptions pertinent to
the schedules covered by this catalog are in Descriptions of Census
Enumeration Districts, 1830-1890 and 1910-1950.
Other Schedules
While their catalog focuses on decennial population schedules, the National
Archives has custody of numerous other Federal census records that can
supplement and enrich genealogical projects and other research. Many of these
records are microfilmed and can be purchased. Schedules of a Special Census
of Indians, 1880 (M1791) reproduces a special 1880 enumeration of Indians
living near military installations in Washington, Dakota Territories, and
California. All other Indians should be enumerated in the state, county, or
locality where they resided. Not until 1890 did the decennial census schedules
enumerate the Indian population with any accuracy. The first listing of all blacks
by name in a Federal census was made in 1870, the first Federal census taken
after the Civil War and the abolition of slavery. In 1850 and 1860, slave
statistics were gathered, but the census schedules did not list slaves by name;
they were tallied unnamed in age and sex categories.
Room for Error
In the 1920 census, for example:
The instructions to the enumerators did not require that individuals spell out
their names. Enumerators wrote down the information given to them; they were not
authorized to request proof of age, date of arrival, or other information.
People were known to change their ages between censuses, and some people claimed
not to know their age. The race determination was based on the enumerator's
impressions. Individuals were enumerated as residents of the place in which they
regularly slept, not where they worked or might be visiting. People with no
regular residence, including "floaters" and members of transient
railroad or construction camps, were enumerated as residents of the place where
they were when the enumeration was taken.
Census years, arranged by content:
The principal topics listed below will indicate how the range of the population censuses grew during the past 2 centuries:
Age and sex, 1790-present (but only
for free Whites until 1820
Slave status, 1790-1860
Color or race, 1790-present (see section below)
Citizenship, 1820-1830, 1870,1890-present
Physical or mental handicap, 1830-1930,
1970-present
Education or literacy, 1840 present
Marital status, 1880-present
Occupation, 1850-present
Industry, 1820, 1840, 1910-present
Employment status, 1880-present (except 1920)
Crime, 1850-1910
Mortality, 1850-1890
Place of birth, 1850-present
Wage rates, 1850-1890
Income, 1940-present
Pauperism, 1850-1860, 1880-1890, 1910
Prisoners, 1880-1910
Institutionalized persons, 1880-1890, 1910
Year of immigration, 1890-1930, 1970-present
Number of children ever born, 1890-1910, 1940-1990
Language (or whether the person could speak
English), 1890-1940, 1960-present
Language of parents, 1910-1920
Spanish/Hispanic origin or descent, 1970-present
[From the Census Bureau's "Factfinder for the Nation, History and Organization," #4, issued May 2000]
Census Records
About.com's "Census Tips and Tutorials" has some of the following sites:
A Beginner's Guide to the U.S. Census--excellent census tutorial and walk-through summary
"Every Ten Years: Key to the United States Census, 1790-1930" a census by census listing of what was recorded (from Genealogy.com)
Ancestry.com's About U.S. Census Population Schedules provides a good look, by census year, of the questions asked and some research tips for using the schedules.
All Vital Records: this is basically a search portal to the Ancestry.com databases but it does give you occurrences of a name in which federal census, as well as some other sources such as state off year censuses. This database includes 456 million names and 10 million census images from 1790 to 1920 but is strictly fee based. A preview listing from any of several censuses is available for viewing. Related to that, but from a different site, is a page on "Deciphering Old Handwriting" which might help in translating some of those census records. See also Cyndi's List for some extensive online selections on old handwriting for personal and place names and occupations, all of which are relevant to census interpretation but would also translate to legal documents and family records of earlier periods.
Calculating Birth Year Based on Census Information
Old and Obsolete Occupations that may help in interpreting enumerators designations or passenger lists
Census worksheets for each decade are available in PDF from the LDS site (www.familysearch.org)
New York State Censuses map show how boundaries have changed over time.
New York State Census Records are available at the New York State Library for on-site researching only. These enumerations, done in non-federal census years were taken at ten-year intervals from 1825 through 1875 and again in 1892, 1905, 1915, and 1925. The microfilm is not for loan and library staff will not search it for patrons. It is also available in LDS Family History Centers.
"The New York State Archives holds the original schedules of the State population census for 1915 and 1925. The schedules are not indexed, and Archives staff will not search them except to provide legal proof of age. The schedules are fragile, and therefore use is restricted. The 1915 and 1925 census schedules and key maps for large cities are available on microform at the State Library. Manuscript schedules of the State census for 1801-1905 were destroyed by fire in 1911. Some county clerks' offices hold duplicate copies of some of the State censuses taken periodically between 1825 and 1925." (quoted from Leaflet #1)
Original records for state pre-1915 censuses are kept at the county level. Availability and location should be determined from the appropriate county clerk's office. To determine the county a particular city is in, refer to the State Library's "Cities, Towns and Villages in New York State." This is an alphabetical list of New York State current cities, tows and villages. For example, the Saratoga County Clerk's Office in Ballston Spa has the bound volumes of the NY State Census available for public use.
Other state's censuses were taken equally randomly and are useful as substitutes or supplements to federal census records that were destroyed or are missing. Also different questions may have been asked, supplying information not normally found in the pro-forma federal census. The previously mentioned "State Census Records" book might help locate these records. Individual states may vary in the amount of web access provided for these censuses. Some like Wisconsin, as well as NYS, show what they have and may even allow searching. A google search on "state censuses" yielded both of these states and a number of others.
New York Census Records is a bibliography of titles and locations relating to state census records