FLORIDA GEOGRAPHIC DATA LIBRARY DOCUMENTATION

TITLE: 1990 U.S. CENSUS URBANIZED AREAS

Geodataset Name:      UA1990
Geodataset Type:      SHAPE
Geodataset Feature:   POLYGON

GENERAL DESCRIPTION:

This dataset contains boundaries for Urbanized Areas as defined by the 
U.S. Census Bureau for the State of Florida. (See "User Notes" below for 
more information.)

DATA SOURCE(S):                   U.S. Census Bureau, Geography Division
SCALE OF ORIGINAL SOURCE MAPS:    VARIABLE
DATE OF AUTOMATION OR SOURCE:     07/18/2001 revised 12/07/2001
GEODATASET EXTENT:                State of Florida

FEATURE ATTRIBUTE TABLES:
Datafile Name:UA1990.DBF

ITEM NAME    WIDTH   TYPE   PRECISION

SHAPE          8   SHAPEPOLY    0
AREA          15   DECIMAL      3
PERIMETER     15   DECIMAL      3
UA             4   CHARACTER    0
NAME          60   CHARACTER    0

FEATURE ATTRIBUTE TABLES CODES AND VALUES:

ITEM           ITEM DESCRIPTION

SHAPE          Data attribute inherent to the ESRI shapefile format, which defines
               the data as a point, polyline, or polygon.

AREA           Area of polygon in square meters

PERIMETER      Perimeter of polygon in square meters

UA             UA/UC 5 digit code

NAME           Name of UA/UC

USER NOTES:

An urbanized area (UA) consists of densely settled territory that contains
50,000 or more people.  A UA may contain both place and nonplace territory.  
The U.S.  Census Bureau delineates UAs to provide a better separation of 
urban and rural territory, population, and housing in the vicinity of large
places.  At least 35,000 people in a UA must live in an area that is not 
part of a military reservation.
For Census 2000, UA delineations constitute a "zero-based" approach that
requires no "grandfathering" of UA boundaries from the 1990 census.  Because of
the more stringent density requirements (and the less restrictive extended place
criteria), some territory that was classified as urbanized for the 1990 census
has been reclassified as rural.  In addition, some areas that were identified as
UAs for the 1990 census have been reclassified as urban clusters.
The title of a UA may contain up to three incorporated place names, and will
include the two-letter U.S.  Postal Service abbreviation for each state into
which the UA extends.  However, if the UA does not contain an incorporated
place, the UA title will include the single name of the geographic entity that
occurs first from the following list:  census designated place, minor civil
division, or populated place recognized by the U.S.  Geological Survey.
Each UA is assigned a five-digit census code in alphabetical sequence on a
nationwide basis, interspersed with the codes for urban clusters (UCs), also in
alphabetical sequence.  For the 1990 census, the U.S.  Census Bureau assigned a
four-digit UA code based on the MA codes.  For Census 2000, a separate flag is
included in data tabulation files to differentiate between UAs and UCs.  In
printed reports, this differentiation is included in the name.
The preceding was taken from the census UA metadata website:
http://www.census.gov/geo/www/cob/ua_metadata.html
Certain scale datasets are not suitable for some project, analysis, or modelling 
purposes.  Please be sure you are using the best available data. 

1:24000 scale datasets are recommended for projects that are at the county
level.  1:24000 data should NOT be used for high accuracy base mapping such as
property parcel boundaries.

1:100000 scale datasets are recommended for projects that are at the
multi-county or regional level.

1:250000 scale datasets are recommended for projects that are at the regional or
state level or larger.

Vector datasets with no defined scale or accuracy should be considered suspect.
Make sure you are familiar with your data before using it for projects or
analyses.  Every effort has been made to supply the user with data
documentation.  For additional information, see the References section and the
Data Source Contact section of this documentation.  For more information
regarding scale and accuracy, see our web pages at:

http://www.geoplan.ufl.edu/education.html
These data are based on interpretation of available information and should
not be construed as legally binding.

FGDL QUALITY ASSURANCE STATUS:

-Reprojected data to FGDL Albers HPGN (See "Map Projection Parameters" below)
-Upcased all character records
-Changed original file name from "Ua99_d90" to "ua1990"
-DESCRIPT item was added based on the item NAME
-Dropped old internal coverage items: UA99_D90#, UA99_D90_ID
-Deleted records of internal polygons that contained no data
-Updated polygon area and perimeter in meters.

DATA LINEAGE SUMMARY:

This dataset was downloaded in shapefile format from the US Census Bureau 
website(http://www.census.gov/geo/www/cob/bdy_files.html). The dataset's 
original geographic extent covered the continetal United States. Hence, 
features within the extent of Florida were selected, then exported to a 
separate shapefile. The shapefile was then reprojected to FGDL Albers HPGN 
(See "Map Projection Parameters" below). Old internal coverage items UA99_D90# 
and UA99_D90_ID were deleted, and records of internal polygons that contained 
no data were deleted. The XTools extension in ArcView was used to update the 
polygon area (in square meters) and perimeter (meters) items in the attribute 
table. 
The dataset's prior history from the US Census is as follows:

The cartographic boundary files are a generalized extract from the U.S. Census 
Bureau's TIGER database. Line simplification/smoothing was performed with a 
tolerance of 0.005 decimal degrees and a coordinate reduction using the Douglas-Peucker
method with a tolerance of 0.0003 decimal degrees. Very small polygons were eliminated
when the combination of geographic codes existed elsewhere. The geography was clipped 
back to the shoreline of the United States, in contrast to TIGER/Line which shows 
the full extent of geography out to the 3-mile limit. These generalized cartographic 
boundary files are originally produced to support the spatial geographic infrastructure 
for certain mapping functions within the Census Bureau's American Fact Finder and in 
support of the LandView Geographic Data Viewer. The generalized files have a much 
smaller file size than the original file extraction from the Census Bureau's TIGER 
database, resulting in faster download and processing times. 

Limitations 
Because of coordinate thinning:Cartographic boundary files should not be used for 
geocoding; Some offshore, redundant, zero population and housing land areas may be 
absent from the files; Cartographic Boundary files are not necessarily vertically 
integrated with previous boundary file sets. This dataset was originally in the 
projection GCS Lat/Lon with a Datum of NAD27. The file was available from the 
website "unprojected".

MAP PROJECTION PARAMETERS:

  Projection                           ALBERS
  Units                                METERS
  Datum                                HPGN
  Spheroid                             GRS1980
  1st standard parallel                24   0  0.000
  2nd standard parallel                31  30  0.000
  Central meridian                    -84   0  0.000
  Latitude of projection's origin      24   0  0.000 
  False easting (meters)               400000.00000
  False northing (meters)              0.00000  

DATA SOURCES CONTACT(S):

Name:      U.S. Census Bureau
Address:   8903 Presidential Parkway, Room 303 WP I
Upper      Marlboro, Maryland 20772
Phone:     301/457-1128	
Web site:  http://www.census.gov/geo/www/ua/ua_bdfile.html	                 
Email:     tiger@census.gov
Contact Person: Geography Division 	
         Phone: 301/457-1128	
         Email: tiger@census.gov                               

FGDL CONTACT:

Name:                    Florida Geographic Data Library
Abbr. Name:              FGDL
Address:                 Florida Geographic Data Library
                         431 Architecture
                         PO Box 115706
                         Gainesville, FL  32611-5706
Web site:                http://www.fgdl.org
Contact FGDL:
      Technical Support:                http://www.fgdl.org/fgdlfeed.html
      FGDL Frequently Asked Questions:  http://www.fgdl.org/fgdlfaq.html
      FGDL Mailing Lists:               http://www.fgdl.org/fgdl-l.html
      For FGDL Software:                http://www.fgdl.org/software.html