Entity_and_Attribute_Overview:
"DATA DICTIONARY
FEATURE TYPE: polygon
NOTES: The original Census TIGER linework is distributed by county.
The county boundaries do not match USGS county linework but do
edgematch seamlessly with each other. We imported data in Decimal
Degrees to maintain the original coordinates. Before further processing,
the fuzzy tolerance was set to 0.000000000001. We dissolved the
coverage on the items FIPS_CTBL and WATER to remove TIGER roads and
streams that split census blocks into multiple polygons. Although most
polygonal water features have unique FIPS_CTBL codes, some share their
code with a block and therefore cannot be uniquely identified.
Remaining extraneous arcs (dangles) were removed by selecting those
arcs where LPOLY# was the same as RPOLY#.
We detected no slivers after mapjoining and the number of unique census
blocks in the final coverage matches the official number from the
Census Bureau. We projected the entire statewide coverage into Teale
Albers projection.
Data from the SF1 file joined to the .PAT with no unmatched records.
Calculate population and housing counts using POP100_DENS and
HU100_DENS, respectively. Create two new numeric fields called PEOPLE and H0USES.
Setting data type to Double with Precision = 12 and Scale = 6 will
minimize rounding error when data are summarized.
Example: [PEOPLE] = [POP100_DENS] * [AREA] * .0000003861003
Assuming AREA is in square meters, this formula calculates number
of people by multiplying population density (per sq mile) by square miles.
Because AREA will change if new polygons are created by clipping or overlays,
AREA must be recalculated (XTools are convenient) followed by PEOPLE and HOUSES.
Housing and population summaries for entire counties may be slightly
different than the official census count because of differences in
TIGER and USGS county linework as noted above.
POP100 and HU100 values are *not* to be used for summary purposes
because they are specific to whole blocks and were carried over from
the raw census data prior to the overlay that determined uninhabitable
areas and split some blocks into multiple polygons.
DATABASE FIELDS: polygon
INPUT OUTPUT DATA DECI
FIELD NAME WIDTH WIDTH TYPE MALS DESCRIPTION
---------- ----- ------ ---- ---- -------------------------------
AREA 8 18 F 5 -
PERIMETER 8 18 F 5 -
CEN00BLM03_1# 4 5 B - -
CEN00BLM03_1-ID4 5 B - -
LOGRECNO 7 7 C - Unique ID for linking to SF1 data
FIPS_CTBL 15 15 C - Full unique identifier for CA
WATER 1 1 I - 1 = Water; 0 = Land
UNINHAB 1 1 I - 1 = Uninhabitable (public land)
EXCLUDE 1 1 I - 1 = Exclude area from density calc.
AREALAND* 8 12 F 2 Area in sq m of block on land from SF1
AREAWATR** 8 12 F 2 Area in sq m of block in water from SF1
POP100 4 10 B - Enumerated population from SF1 file
HU100 4 10 B - Enumerated housing units from SF1
TOT_SQ_MILES 8 12 F 4 Area of original block (all polys)
HAB_SQ_MILES 8 12 F 4 Total habitable area of block
POP100_DENS 8 12 F 2 Pop. density based on HAB_SQ_MILES
HU100_DENS 8 12 F 2 Housing density based on HAB_SQ_MILES
DENCLASS10 2 2 I - Housing density class (see below)
** REDEFINED ITEMS **
STATE 2 2 C - 2 character FIPS State code
COUNTY 3 3 C - 3 character FIPS County code
TRACT 6 6 C - 6 character TRACT code
BLOCK_GROUP 1 1 C - 1 character BLOCK GROUP code
BLOCK 3 3 C - 3 character BLOCK code
* AREALAND contains the area of the entire land portion of the block for a
unique LOGRECNO. Thus, if the block is composed of two or more polygons,
AREALAND will not agree with the ARC/INFO calculated AREA measurement of the
individual polygons.
** In come cases, WATER = 1 but AREAWATR = 0. These appear to be dry lake
beds. Although dry lake beds are habitable, we have excluded them from the
calculation of HU100_DENS because there are blocks that have both wet and
dry lake beds. Because the data provide no way to discern wet and dry lake
beds within a block, assigning density to the dry lakes but not the wet
lakes is not possible. Therefore, we exclude all lake beds (WATER = 1)
from density calculations regardless of AREAWATR.
FIELD NAME: LOGRECNO and FIPS_CTBL
Unique identifier for the smallest statistical and geographic unit
captured by Census. FIPS_CTBL is a concatenation of FIPS STATE
CODE + COUNTY FIPS CODE + TRACT CODE + BLOCKGROUP CODE + BLOCK CODE.
FIPS_CTBL has a one to one relationship with LOGRECNO. LOGRECNO is
the unique key field used by Census in the SF1 attribute table.
FIELD NAME: WATER
Water polygon from US Census TIGER data. Considered uninhabitable and
excluded from calculation of HAB_SQ_MILES.
FIELD NAME: UNINHAB
Public lands from GOVCONFEE02_1 that generally do not contain public
habitation or developed areas. These areas were excluded from
calculation of HAB_SQ_MILES. CDF-FRAP considered the following public
ownership classes 'habitable' and therefore did not exclude census
counts. Although large portions of some of these ownerships may indeed
be uninhabitable (such as DoD lands), no such delineations exist and
significant numbers of people do reside on these lands. In contrast,
although people do reside in National Parks (such as Yosemite Valley),
these numbers are small and the vast majority of the NPS lands are
uninhabited.
Tribal Lands
Department of Defense (except Army Corps of Engineers)
State Dept of Corrections
State Hospitals
California State University
University of California
California National Guard
FIELD NAME: DENCLASS10
DENCLASS10 HOUSING DENSITY
-------- ---------------
1 NONE
2 LESS THAN 1 UNIT PER 160 ACRES (< 4 / Sq. mi.)
3 1 UNIT PER 160 ACRES TO 1 UNIT PER 40 ACRES (4 - 16 / Sq mi)
4 1 UNIT PER 40 ACRES TO 1 UNIT PER 20 ACRES (16 - 32 / Sq mi)
5 1 UNIT PER 20 ACRES TO 1 UNIT PER 10 ACRES (32 - 64 / Sq mi)
6 1 UNIT PER 10 ACRES TO 1 UNIT PER 5 ACRES (64 - 128 / Sq mi)
7 1 UNIT PER 5 ACRES TO 1 UNIT PER 1 ACRE (128 - 640 / Sq mi)
8 1 UNIT PER 1 ACRE TO 2 UNITS PER ACRE (640 - 1280 / Sq mi)
9 2 UNITS PER 1 ACRE TO 5 UNITS PER ACRE (1280 - 3200 / Sq mi)
10 GREATER THAN OR EQUAL TO 5 UNITS PER ACRE (>= 3200 / Sq mi)"