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************ MUNICIPAL BOUNDARY COVERAGE DOCUMENTATION ***************** The export files [cnty]95pl.e00 import into coverages with municipal boundaries by county. There was no compression on the EXPORT (i.e. We used the 'none' option). The municipal boundaries in these coverages were orignially extracted from the Census Bureau's Tiger94 dataset (input scale 1:100,000). We have made additional modifications to the boundaries to reflect the current municipal geography (up through December 1996). Any annexation activity that has occurred since January 1, 1990, is shown in the data set*. The Division of Local Government is required by law to maintain a file of boundary changes to municipalities within Colorado. When an annexation occurs the city files two copies each of the ordinance and plat to the county, who approves and forwards the extra set on to us. We convert the information into our GIS and code the graphics so that it can be related back to our annexation database. Polygons that are coded as annexations also preserve the history of boundary changes**. Data conversion is done primarily with the Arc/Info COGO (Coordinate Geometry) module which converts an annexation's legal description metes and bounds into a digital, positionally accurate version of the traverse. Many annexations which occurred between 1990 and 1994 were included in the Census Bureau's Tiger files. Other sources for digital annexation data were the Colorado Department of Transportation and sometimes DXF files provided by the municipality. The boundary change source is indicated in the 'BNDSOURCE' item (see below). We have also assigned a value of relative quality for the boundary source input method. The coverages have the following items in their polygon attribute table ([cnty]95pl.PAT): COL ITEM NAME WDTH OPUT TYP N.DEC ALTERNATE NAME explanation ------------------------------------------------------------------------ 1 AREA 8 18 F 5 9 PERIMETER 8 18 F 5 17 BOUL94PLACE# 4 5 B - 21 BOUL94PLACE-ID 4 5 B - 25 PLACEFP 5 5 I - place fips 30 PREV_FPL 5 5 I - previous placefp 35 BND_DATE 8 8 D - date passed 43 BND_FLAG 3 3 C - (see codes below) 46 COUNTY 3 3 I - CNTY county fips 49 RECP_NUM 8 8 C - RECP.NUMBER annex reception# 57 BND_SOURCE 7 7 C - boundary source 64 QUALITY 1 1 I - boundary quality (see codes below) Codes for BND_FLAG (flags boundary change) AN = annexation DT = detachment CQR = count-question resolution (blank) = indicates boundary during 1990 census Codes for BND_SOURCE TIGER94 = boundary from Tiger94 COGO = boundary entered with COGO by DLG Cartography/GIS section CDOT = boundary digitized by Colorado Department of Transportation DIG = boundary digitized by DLG Cartography/GIS section DXF = boundary provided in digital format by municipality Codes for QUALITY 1 = Highest quality (eg COGO source, dxf file) 2 = (digitized from good paper map) 3 = (Tiger94 source) 4 = Lowest quality (digitized from poor paper map) A related data file named [cnty]96pl.nam contains the names of the municipalities in each county. It can be related [cnty]96pl.pat based on the item PLACEFP. These data are on an annual update cycle. COORDINATE SYSTEM DESCRIPTION Projection UTM Zone 13 Datum NAD83 Units METERS Spheroid GRS1980 Xshift 0.00000 Yshift 0.00000 * Disclaimer: Inaccuracies may and probably do exist due to boundary information obtained from various sources and scales. There is also the possibility that we did not receive record of an annexation, which would therefore not be reflected in the dataset. ** These interior boundaries may be 'dissolved' on the common value of the item PLACEFP if they are not desired. |
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