Public Law 94-171 (Redistricting File)

Public Law 94-171 (Redistricting File) - 2000 (pl942000)

Overview

These files provide some basic population counts from the 2000 decennial census. Total persons and a breakdown of persons by 6 major race categories and by voting age is provided. Hispanic origin counts are also provided, combined with race and voting age.

These files provide very fine geographic detail, with summaries for areas ranging from the entire U.S. to a census block. There are dozens of geographic summary levels provided.

The original files provided from the U.S. Census Bureau had a full set of over 270 data cells for each geographic area. In processing the file the Missouri Census Data Center has attempted to provide more compact and, we hope, easier to use data summaries. Most of the data sets found here are compact summaries data sets in which each observation (row) corresponds to one geographic entity (a census tract or a county, for example) and the variables are a set of about 34 key items gleaned from the over 270 cells on the orginal summary record. In many cases, we have done aggregation to create summaries for geographic entities that were not summarized on the orginal files (for example, Metropolitan Statistical Areas for the U.S. and School Districts in Missouri.)

Geographic Coverage

The data covers the entire country. We have a few more geographic units summarized for Missouri, but the basic data down to the census block level is available for all states. Generally, the coverage of each data file varies and is identified by the first two letters of the file name, which is either us or a state postal abbreviation such as mo, ca, il, etc.

Data Set Organization and Naming Conventions

Sets for All States

For each state we have created a series of SAS data sets and views (we do not count index files as SAS data sets.) A view is just like a data set for you, the user. Internally, however, it is not stored as an actual data set, but instead as a series of SAS SQL commands that generate a data set when you reference the view. SAS data sets and data views are referred to as "SAS data files". These data files have names that begin with the state postal code. For example, the data files for the state of Alabama (postal code "al") are

algeos -- Contains geographic identifier data only for all geographic summaries in the state.
aldetail -- Harder to explain. You probably won't want to access this data set. Essentially we took the 274 cells of the orginal summary tables as provided by the Census Bureau and created this data set with one observation per non-zero cell of those tables. If you are familiar with dimensional data warehousing concepts, you would recognize that we have create a poor man's DDW and this is the fact table. We use this table to build the sums data sets. It has a series of dimension variables (geo_id, race_id, hispanic and voteage) and a single fact variable, persons, that tells us the number of people who were reported in the category. So the first observation on the aldetail data set has these values:
- geo_id: 1 Points to the first observation on the algeos data set describing the state of Alabama. (If the value was 2 it would mean this was data for Autauga county, the 2nd observation on the algeos set.)
- race_id: 1 Respondents could choose up to 6 race categories. We assinged numeric codes to the 63 possible combinations. The code 1 means they checked "White" and no other race category. So this observation is for people who are "White alone".
- hispanic: 0 This means non-hispanic. The people being summarized on this record indicated they were not of hispanic origin. (The value would be 1 if we were summarizing people who indicated they were hispanic.)
- voteage: 0 This means we are looking at people who are not yet of voting age, i.e. are below the age of 18.
- persons: 711149 This is our count, our "fact" about the category. There were 711,149 people who were identified as being in the state of Alabama, who said they were white alone, non-hispanic and under the age of 18.
alsumsng -- We aggregated the data from aldetail to create summaries for the distinct values of geo_id (i.e. for each of the geographic entities.) We were particular about who we chose to summarize. We did not feel there would be sufficient interest in items such as the number of persons reporting they were of any specific multiracial group. Except that we thought it important to know how many people reporting each race reported that race exclusively, or in conjunction with other races. We calculated only 34 summary items as follows:
- Total Persons (1)
- Persons by Race alone (6)
- Persons by Race alone or in combination (6)
- Persons of hispanic origin (1)
- White alone non-hispanic and white-alone-or-in-combination non hispanic (2)
- Persons who reported multiple races (1)
- Repeat all of the above for persons over 18 (34)
The "ng" at the end of the set name stands for "no geography". Which means these data sets have no detailed geographic information. But they do contain the key variable geo_id. See the next data set.
alsums -- This is a view set that combines the data in algeos and algeosng. Using the geo_id key to perform the "joining" of these two data sets lets us have our summary observations with all the very detailed geographic information without having to waste space on the data archive repeating all the geographic information. It remains in algeos, and gets automatically linked with the demographic summaries in algeosng as needed. This is the data set that should be of most interest to most users. It is important to understand that this data set can be displayed and utilized without having to understand a word of our attempt here to explain a little about how this data set was derived.
The following are all views derived from the alsums data file
alstcnty -- The state summary plus all counties.
alvtds -- Voting district summaries.
almcds -- MCD (county subdivision) summaries.
alplaces -- Place summaries, levels 155 and 160 (i.e. place-within-county and complete place).
altracts -- Census tract summaries.
alblocks -- Census block summaries.

Remember -- all these data files are available for all states. Just as there is an altracts data file with data for Alabama, there are also njtracts and catracts data files with data for New Jersey and California, etc.

Missouri Only Data Sets

There are a number of data sets that exist only for Missouri. These are mostly custom aggregations of the data to different geographic units. These sets are name beginning with mo followed by the geographic units summarized within the data set. For example, morpcs.sas7bdat contains summaries for Missouri Regional Planning Commissions, and mobgs150.sas7bdat contains data summarized for census block groups. (The files as released contain summaries for block groups split by several higher level geographies, namely VTD, MCD and place, but many users just want a summary for complete block groups.)

United States Coverage Data Sets

We have extracted and/or aggregated data in the 51 state level data sets to create a series of national data sets. Each of these data sets has a name beginning with us. These sets provide summaries for the entire U.S., its regions and divisions (in the set usregdiv.sas7bdata), for states (usstates), for counties and equivalents (uscntys), metropolitan areas (2000 definitions) (usmetros, and places (cities) with at least 2500 population (usplaces). There is also a data set, uscntychange, that combines the TotPop count from pl942000 with the revised 1990 count and all annual intercensal estimates by year.

And New England Towns

Minor Civil Divisions are known as towns in New England. Because they are used as the building blocks for metro areas there, we created a separate data set with the MCD-level summaries for that entire region. This data file is called NewEnglandMCDs.sas7bdat.

Codebook - Description of the Variables/Columns in Each Data File

Not all variables occur in all data sets, especially the identifier variables. Does not apply to xxdetail datasets.

Geocodes and Other ID Variables

For a more detailed description of (most of) these codes see the Identification Section (within the Data Dictionary, Chapter 7) of the Census Bureau's official technical documention.
esriid
Occurs only on selected data views. This was our attempt to create a single character string key that would provide a linkage to Arcview shape files being provided by various sources. These strings are just a set of geographic code values strung together.
geo_id
A sequentially assigned numeric key that links the data back to the state's geos data file.
geocode
Our locally generate concatenation of geographic code separated by dashes that uniquely ID the area. Not as useful as we had hoped. Probably best to ignore it.
sumlev
Geographic Summary Level code .

SUMLEV Code Summary Level

040 State

050 County (or county equivalent)

060 County subdivision (MCD, township, CCD)

140 Census tract (complete)

155 Place (within county)

160 Place (complete)

500 Congressional District (106th)

610 State Senate District (as of 2000)

620 State House District (as of 2000)

700 VTD (Voting Tabulation District)

740 Block Group, split by VTD, MCD, and Place

750 Census Block Note: On Summary File 1, block summaries have a SUMLEV code of '101'.
What's the difference? Sort order, we guess. To us, a census block is a census block --
it cannot be split by anything because it is by definition the smallest thing
there is in terms of census geography.

areaname
Name of the geographic area being summarized.
state
FIPS state code.
stab
State postal abbreviation.
county
5-digit FIPS county code. Will sometimes print as the county name because $county. format code has been permanently assigned to it.
tract
Census tract in tttt.tt format. Leading and trailing zeroes coded. Tract codes are unique within counties and all areas are assigned a tract code.
logrecno
Logical Record Number. Important when reading the orginal set of 40 files that were used to create these data sets. Not nearly as interesting here, but it does form a link back to the orginal raw data files and could be used as a link variable, though we prefer to use geo_id for that purpose.
region
U.S. Region
division
U.S. division.
statece
Census state code. Rarely used any more. Use the FIPS code.
cnty
County code (3-digit version) -- See county variable, above, which is 5 characters and includes the state code.
cntysc
County size code.
cousubfp
County subdivision (MCD) FIPS code. Unique within state. (The census 3-digit code for these entities that was unique within county and was used in earlier censuses is not included on 2000 files.) available.)
cousubcc
County subdivision class code.
cousubsc
County subdivision size code.
placefp
Place FIPS code. Unique within state. (The The census 4-digit place code that was used in earlier censuses is not included on 2000 files.) A values of 99999 is sometimes used to indicate a non-place remainder of an area, where "non-place" means not incorporated and not in a census designated place.
placecc Place class code.

placedc Place description code.

placesc
Place size code.
bg
Block group. (First digit of block on block level observations.) Block groups are unique within census tracts.
block
Census Block. A 4-digit code this decade, the first digit being the block group. In 1990 the blocks codes were 3 digits with an optional alpha suffix. In 1970 and 1980 blocks were just 3 digits. This is the smallest geographic level that the census recognizes. Blocks are unique within census tract, which are unique within county.
concit Consolidated city.

msacmsa
Metropolitan Statistical Area/Consolidated MSA. As of Jan. 1, 2000 we think.
masc
Metropolitan Area Size Code.
cmsa2
Two-digit code for CMSA.
macci
Metropolitan area central city indicator.
pmsa
Primary MSA.
necma
New England County Metropolitan Area code. N.A. outside New England.
urbanrur
Urban Rural code - would be very valuable but it is NOT defined on pl94. (Maybe later we can add it.) For now, the field is always blank.
cd106
Congressional District - 106th (1998)
sldu
State Leg District Upper Chamber (Senate district in Missouri)
sldl
State Leg District Lower Chamber (House district in Missouri)
vtd
Voting Tabulation District. How these are assigned and documented varies from state to state and sometimes from county to county. Used almost exclusively in redistricting applications.
vtdi
VTD indicator to indicator if it is a real or pseudo VTD.
zcta3
3-digit ZCTA code - not used on pl94.
zip
ZIP Census Tabulation Area - not used on pl94.
arealand
Land Area in Square Meters
areawatr
Water Area Sq Meters
funcstat
Functional Status Code.
gcuni
Geographic Change User Note Indicator.
pop100
100% Population Count. Should be the same as TotPop on these files.
intptlat
Internal point north latitude. Accurate to 6 decimal places.
intptlon
Internal point west longitude (will be negative). Accurate to decimal places.
lsadc
Legal/Statistical Area Description Code. See format code for values.
partflag
Blank for many summary levels. Where used, values are "P" to indicate an area that is split (e.g. just part of a tract or BG), or "W" to indicate this is the whole area.
sdelm
Elementary school district (NCES code) This and the other 2 school codes appear on the block level summaries only. To get data by school district you have to sum data at the block level.
sdsec
Secondary school district (NCES code) NA for Missouri.
sduni
Unified school district (NCES code).
taz
Transportation Analysis Zone. This code appears on block level summaries only.
uga
Urban growth area. Only relevant in state of Oregon.
puma5
PUMA Code as used on 5% PUMA files. NA on pl94 files.
puma1
PUMA Code as used on 1% PUMA files. NA on pl94 files.
landsqmi
Land Area Sq Miles - derived from value in square meters.
areasqmi
Total Area Sq Miles - derived from AreaLand + AreaWatr and converted to square miles.

Tabular Data

totpop
Total Population.
white1
White alone : Persons who checked the "White" option and no other in response to the race question.
white2
White alone or in combination : Persons who checked the "White" option in response to the race question (regardless of whether or not they checked any other).
Each of the following pairs of race counts use comparable definitions, i.e. they report persons who checked only that race and persons who checked that race regardless of what else they checked.
black1
Black alone
black2
Black alone or in combination
indian1
Amer Indian alone
indian2
Amer Indian alone or incombination
asian1
Asian alone
asian2
Asian alone or in combination
hawnpi1
Hawaaian or PI alone
hawnpi2
Hawaaian or PI alone or in combination
other1
Some Other race alone
other2
Some other race alone or in combination
whitenh1
White alone, Non Hispanic
whitenh2
White alone or in combination, Non Hispanic
hisppop
Hispanic Population . This is not a race. On the census questionnaire, there is a question regarding race that does not have hispanic as one of the choices. Instead, there is a separate question asking if you are hispanic. Thus, a person can be both white and hispanic, or both black and hispanic.
over18
Population Aged 18 and over.
whovr181
White alone, over 18
whovr182
White alone or in combination, over 18
blovr181
Black alone, over 18
blovr182
Black alone or in combination, over 18
inovr181
AIAN alone, over 18
inovr182
AIAN alone or in combination, over 18
asovr181
Asian alone, over 18
asovr182
Asian alone or in combination, over 18
haovr181
Hawaaian or PI alone, over 18
haovr182
Hawaiian or PI alone or in combination, over 18
otovr181
Other race alone, over 18
otovr182
Other race alone or in combination, over 18
wnovr181
White Non-hisp alone, over 18
wnovr182
White Non-hisp alone or in combination, over 18
hisovr18
Hispanic Pop Over 18
multrace
Multi Racial - Persons who checked more than one race.
mrovr18
Multi Racial Over 18

Missouri Census Data Center

URL: mcdc2.missouri.edu/pl942000/Readme.html
jgb

SUMLEV Code	Summary Level
040	State
050	County (or county equivalent)
060	County subdivision (MCD, township, CCD)
140	Census tract (complete)
155	Place (within county)
160	Place (complete)
500	Congressional District (106th)
610	State Senate District (as of 2000)
620	State House District (as of 2000)
700	VTD (Voting Tabulation District)
740	Block Group, split by VTD, MCD, and Place
750	Census Block Note: On Summary File 1, block summaries have a SUMLEV code of '101'. What's the difference? Sort order, we guess. To us, a census block is a census block -- it cannot be split by anything because it is by definition the smallest thing there is in terms of census geography.