o Universe: 

Information from the censuses were derived either from questions asked
of the entire population or from questions asked of only a sample of the
population. Those questions asked about every person and housing unit
are called 100-percent or short-form questions. The others are called
sample or long-form questions.

Those households receiving the short-form questionnaires were asked only
the 100-percent questions, and those receiving the long form were asked
both the 100-percent questions and the sample questions. In 1990, some
17.7 million housing units received a long form, out of an estimated
total of 106 million units (about 16.7%). Sampling rates vary depending
on geographic location and population size.

PUMS datafiles contain a sample of the individual long-form census
records showing most population and housing characteristics with
identifying information removed.

STF datafiles contain pre-tabulated results (counts) of the short or
long form census records. STF datafiles may contain census information 
at very small geographic areas.


      Household Relationship, Sex, Race, Age, Marital Status, Hispanic
      Number of units in structure, Number of rooms in unit, Tenure
      (owned or rented), Value of home (or monthly rent), Congregate
      housing (meals included in rent), Vacancy characteristics. 


   Population: Social Characteristics 
      Education (enrollment and attainment), Place of birth,
      Citizenship, Year of entry to U.S., Ancestry, Languague (spoken
      at home), Migration (residence between decennial censuses),
      Disability, Fertility, Veteran Status. 
   Population: Economic Characteristics 
      Labor force, Occupation, Industry, Class of worker, Place of
      work, Journey to work, Work experience, Income, Year last worked.
      Year moved into residence, Number of bedrooms, Plumbing, Kitchen
      facilities, Telephone in unit, Vehicles available, Heating Fuel,
      Source of water, Method of sewage disposal,Year structure built,
      Farm residence, Shelter costs (including utilities). 

o Design and Methodology:

The coding system varies for each census, so it is important to have
access to the codebook for each census in order to assess the meaning of a
specific field in a census record and its comparability across censuses.
Very little comparability exists between geographic identifiers on each of
the previous files, but housing and population characteristics are
similar. Because of this similarity, census datafiles can be 
useful for analysis of trends.

The sample questionnaires were edited for completeness and consistency,
and substitutions or allocations for any missing data were made.
Allocation flags may appear within microlevel data to indicate when an 
item has been allocated. Tabulated data may contain imputation fields
for selected tables.

o Variables (reported in PUMS):

  o Items in the housing record might include: 

    allocation flags for housing items; bedrooms; condominium status;
    contract rent; cost of utilities; family income; family, subfamily, and
    relationship recodes; farm status and value; fire, hazard, flood
    insurance; fuels used; gross rent; house heating fuel; household
    income; household type; housing unit weight; kitchen facilities;
    linguistic isolation; meals included in rent; mortgage status and
    selected monthly owner costs; plumbing facilities; presence and age of
    own children; presence of subfamilies in household; property value;
    real estate taxes; rooms; sewage disposal; source of water; state;
    telephone in housing unit; tenure; units in structure; vacancy status;
    vehicles available; year householder moved into unit; and year
    structure built. 

  o Items in the person record might include: 

    ability to speak English; age; allocation flags for population items;
    ancestry; children ever born; citizenship; class of worker; disability
    status; educational attainment; Hispanic origin; hours worked; income
    by type; industry; language spoken at home; marital status; means of
    transportation; migration PUMA; migration state; military status,
    periods of active duty military service, veteran period of service;
    mobility status; occupation; person's weight; personal care limitation;
    place of birth; place of work PUMA; place of work state; poverty
    status; race; relationship; school enrollment and type of school; time
    of departure for work; travel time to work; vehicle occupancy; weeks
    worked; work status; work limitation status; and year of entry.

Summary Tape Files (STF) are designed to provide statistics with greater
subject detail for geographic areas than is feasible or desirable to provide
in printed reports. The census data contained in printed reports are arranged
in tables. Population and housing characteristics are presented for specified
geographic areas; for example a table may represent the number of rented
housing units in a census tract, the number of persons 65 years of age or
older in a city, or the total population of a county. Census data at the
small-area level, such as census tracts and smaller, will contain limited
subject matter detail. STF files, in machine readable format, mimic this
table layout.

 Introduction to Summary Tape File 3.

 This database consists of four sets of computer-readable data files
 containing detailed tabulations of the nation's population and housing
 characteristics. The files contain sample data inflated to represent the
 total United States population. The file also contains 100 % counts and
 unweighted sample counts of persons and housing units. This series is
 comprised of STF3A, STF3B, STF3C, and STF3D. All files in the STF3 series
 are identical, containing 3,300+ table cells, as well as standard
 geographic identification variables. Population items tabulated for each
 person include demographic data and information on schooling, ethnicity,
 labor force status, children, and details about occupation and income.
 Housing items include data on size and condition of the housing unit as
 well as information on value, age, water, sewage and heating, vehicles,
 and monthly owner costs. Each file provides different geographic coverage.


    provides summaries for the divisions (MCDs) or census county divisions
    (CCDs), places or place segments within MCD/CCDs and remainders within
    MCD/CCDs, census tracts or block numbering areas (BNAs) and block
    groups (BGs) or, for areas that are not block numbered, enumeration
    districts (EDs), places, and Congressional Districts.

Standard Extracts (Variable listing of the CSV files): 

       From the 3,300+ table cells available (containing only count data), 
       the following variables will be generated in the standard extract
       files at several census geographies including county, tract, 
       blockgroup, minor civil division, place. These data will also be
       aggregated to zipcodes (5-digit) and Metropolitan Statistical Area.

         totpop   total persons 
         landsqmi land area in sq miles
         poppsqmi persons per square mile (land)
         female   female pop
         rural    persons in rural areas
         onfarms  persons on farms
         infamily persons in families
         alone    persons living alone
         groupqtr persons in group quarters
         pctfemal pct female 
         pctgq    pct persons in grp qtrs
         white    white pop
         black    black pop
         asianpi  asian & pac islandr pop
         amindian am indian, esk, aleuts pop
         hispanic persons of hispanic origin
         pctwhite % white pop
         pctblack % black pop
         pctasian % asian + pi pop
         pctamind % am indian, esk, aleuts
         pcthisp  % hispanic pop

         age structure breakdown ... percentages
         pct0_4    pct5_9    pct10_13  pct14_17  pct18_24  
         pct25_34  pct35_44  pct45_54  pct55_59  pct60_64  
         pct65_74  pct75_84  pct85_up  
         pct0_19   pct20_39  pct40_64  pct65_up
         pct0_9    pct0_13   pct0_17   pct0_24   pct0_34   
         pct0_44   pct0_54   pct0_59   pct0_64   pct0_74   
         age structure breakdown ... counts
         age0_4    age5_9    age10_13  age14_17  age18_24  
         age25_34  age35_44  age45_54  age55_59  age60_64  
         age65_74  age75_84  age85_up  
         age0_19   age20_39  age40_64  age65_up
         age0_9    age0_13   age0_17   age0_24   age0_34   
         age0_44   age0_54   age0_59   age0_64   age0_74   

         medage   median age
         tothhs   total households
         avghhsz  persons per household
         hhs1     1-person hshlds age 65+
         hhs2     2-person households
         hhs3_4   3-4 person households
         hhs5_up  5+ person households
         pcthhs1  % 1-person households
         pcthhs2  % 2-person households
         pcthhs3_ % 3-4 person households
         pcthhs5_ % 5+ person households
         families total families
         mcfams   married couples
         mcwchild :with related children
         femhead  female headed family, no husband present
         femheadc :with related children
         nonfhhs  non-family households
         pctmcfam % of families, married couples
         pctmcwch % :with related children
         pctfemhe % female headed fam, no husbnad present
         pctfemhc % :with related chldren
         pctnfhhs % non-family households

         income breakdowns ... counts
         hhi0_10  households with income < $10000 1989
         hhi10_15 households with income $10k - $14,999
         hhi15_25 households with income $15k - $24,999
         hhi25_35 households with income $25k - $34,999
         hhi35_50 households with income $35k - $49,999
         hhi50_75 households with income $50k - $74,999
         hhi75_99 households with income $75k - $99,999
         hhi100up households with income $100,000 & up
         income breakdowns ... percentages
         phi0_10  % househlds with income < $10k '89
         phi10_15 % househlds with income $10k - $14,999
         phi15_25 % househlds with income $15k - $24,999
         phi25_35 % househlds with income $25k - $34,999
         phi35_50 % househlds with income $35k - $49,999
         phi50_75 % househlds with income $50k - $74,999
         phi75_99 % househlds with income $75k - $99,999
         phi100up % househlds with income $100,000 & up
         phi0_15  % househlds with income < $14,999
         phi0_25  % househlds with income < $24,999
         phi0_35  % househlds with income < $34,999
         phi0_50  % househlds with income < $49,999
         phi0_75  % househlds with income < $74,999
         phi0_99  % househlds with income < $99,999
         other ...
         medhhinc median household income 1989
         famwork0 families with no workers in 1989
         famwork1 families with 1 worker in 1989
         famwork2 families with 2 workers in 1989
         famwork3 families with 3+ workers in 1989
         avgfami0 average family income: fams w 0 wrkrs 1989
         avgfami1 average family income: fams w 1 wrkr 1989
         avgfami2 average family income: fams w 2 wrkrs 1989
         avgfami3 average family income: fams w 3+ wrkrs 198
         medfamin median family income 1989
         avgfamin average family income 1989
         pci      per capita income
         pcihhs   per capita income, persons in hhs

         poor     persons below poverty level
         verypoor persons below 50% of poverty level
         pooruniv persons for whom poverty status determined
         pctpoor  % persons below poverty level
         pctveryp % persons below 50% poverty level

         elemeduc pop > 25 less than 9th grade ed
         highsch1 pop > 25 9-12th grade no diploma
         highsch2 pop > 25 high school graduate
         college1 pop > 25 some college no degree
         college2 pop > 25 associate degree
         college3 pop > 25 bachelor's degree
         college4 pop > 25 graduate or professional degree
         pctelem  % elementary education only
         pcthsch1 % 9-12th grade no diploma
         cthsch2  % high school graduates
         pctcoll1 % some college, no degree
         pctcoll2 % associate degree
         pctcoll3 % bachelor's degree
         pctcoll4 % graduate or prof. degree
         pctnhsgr % not high school graduates
         pctnocol % no college
         pctnodeg % no college degree
         pctnobac % no bachelor's degree
         pctnogrp % no graduate/prof degree

         clf      civilian labor force 16+
         unemplyd unemployed persons 16+
         empovr16 employed persons 16+
         unempfem unemployed female in civilian labor force
         emplyfem employed females
         pctunemp civilian labor force unemployment rate, 1989
         clffem   women in the civilian labor force 1989
         nonclff  women over 16 not in civilian labor force '89
         ctunemf  civilian labor force unemployment rate females 89
         mgrprof  managerial & pr0. specialty occs
         techsadm technical, sales, admin support
         servoccs service occupations
         farmetc  farm, forestry & fishing
         otherocc other occupations
         pctmgpr  % managerial & pro specialty occs
         pcttechs % technical, sales, admin support
         pctserv  % employed in service industries
         pctfarme % employed in farm, foresty, fishing
         pctothoc % employed in other occupations

         totunits total housing units
         occunits occupied housing units
         vacant   vacant housing units
         ownerocc owner occupied housing units
         rented   renter occupied housing units
         units1   single family units
         units5up units in 5+ unit buildings
         mobilhms mobile homes
         condos   condominium units
         pctunit1 % single family units
         pctunit5 % units in 5+ units buildings
         pctvacnt % vacant units
         pctowner % all units owner occ
         pctrentr % all units renter occ
         medyrblt median year built
         builta85 units built 1985 - 3/90
         built80_ units built 1980 - 3/90
         built70_ units built 1970-1979
         built60_ units built 1960-1969
         built50_ units built 1950-1959
         built40_ units built 1940-1949
         builtp40 units built before 1940
         pctbltmd % units built busiest decade
         pctblt85 % units built 1985-3/90
         pctblt40 % units built before 1940
         avghval  average value, owner units
         medhval  median value, owner units
         untscrnt sepcified renter units with cash rent
         medrent  median gross rent