Assessment-standard projection: Projection: Albers Equal Area Units: Meters Spheroid: GRS80 Datum: NAD83 First Standard Parallel: 27 degrees 30 minutes Second Standard Parallel: 37 degrees 30 minutes Central Meridian: -90 degrees 00 minutes Latitude of Origin: 25 degrees 00 minutes False Easting: 0.0 False Northing: 0.0
USGS Process Description: The data was extracted from Census TIGER/line files stored on 38 compact discs (CD) using the following four step procedure: 1) Copy the data off the TIGER/line CD onto magnetic disc of a Data General 6220 server. The data was copied on a per state basis under an individual directory. 2) Run the data through ARCTIGER.AML which goes as follows: /* ARCTIGER.AML - An aml that will extract county outer boundary lines from /* Census TIGER line files and MAPJOIN these lines to create a /* full state coverage of county lines. Directory must contain /* albers.prj Projection file. /* -------------------------------------------------------------------------- /* Read county list from a particular state and set # of iterations to the /* # of counties. &args stno state &setvar countycount [filelist /gis/%stno%[unquote '/*'] county.list -full -dir] &setvar fileunit [open county.list ostat -r] &do i = 1 &to %countycount% /* Read individual TIGER files. &setvar cty [locase [read %fileunit% rstat]] &setvar xyz [filelist %cty%/tgr* tigerfiles -full -file] &setvar filunit [open tigerfiles ostat -r] &sv fname [locase [read %filunit% rstat]] &sv statecounty [substr %fname% 16 5] /* Block TIGER file record 1 and perform SORTTIGER. &if [after %fname% .] = f21 &then &sys dd if=%fname% of=line%statecounty% ibs=228 obs=228 cbs=228 conv=unblock sorttiger 1 line%statecounty% lnsrt%statecounty% &sv fname [locase [read %filunit% rstat]] /* Block TIGER file record 2 and perform SORTTIGER. &if [after %fname% .] = f22 &then &sys dd if=%fname% of=shape%statecounty% ibs=208 obs=208 cbs=208 conv=unblock &sv cerr1 [close %filunit%] sorttiger 2 shape%statecounty% shpsrt%statecounty% /* Create ARC coverage from blocked and sorted TIGER files using the /* TIGERARC command. tigerarc precensus geo%statecounty% lnsrt%statecounty% shpsrt%statecounty% &sys rm line%statecounty% lnsrt%statecounty% shape%statecounty% ~ shpsrt%statecounty% build geo%statecounty% line /* Extract items geo%statecounty%-ID and SOURCE from geo%statecounty%.ACODE /* datafile and add to geo%statecounty%.AAT pullitems [translate geo%statecounty%].ACODE PULL [translate geo%statecounty%]-ID SOURCE END joinitem [translate geo%statecounty%].AAT PULL ~ [translate geo%statecounty%].AAT [translate geo%statecounty%]-ID ~ [translate geo%statecounty%]-ID ORDERED tables $kill PULL q stop /* Project geo%statecounty% into Albers equal area to create prj%statecounty%, /* BUILD with LINE, CLEAN with 10 10 POLY and extract outer boundary to create /* cov%statecounty%. project cover geo%statecounty% prj%statecounty% albers.prj build prj%statecounty% line clean prj%statecounty% gcl%statecounty% 10 10 poly reselect gcl%statecounty% cov%statecounty% line RESELECT LPOLY# = 1 OR RPOLY# = 1 [unquote ' '] n n build cov%statecounty% line build cov%statecounty% poly /* ADDITEM STATECTY and populate cov%statecounty%.PAT with %statecounty%, /* calculate cov%statecounty%-ID in the cov%statecounty%.AAT to equal SOURCE /* so pseudonodes can be deleted with UNSPLIT in ARCEDIT, then set all /* cov%statecounty%-ID's in cov%statecounty%.AAT to equal /* cov%statecounty%#. createlabels cov%statecounty% build cov%statecounty% poly additem [translate cov%statecounty%].PAT [translate cov%statecounty%].PAT ~ STATECTY 5 5 I tables select [translate cov%statecounty%].PAT reselect [translate cov%statecounty%]# GT 1 calc STATECTY = %statecounty% select [translate cov%statecounty%].AAT reselect SOURCE CN ' ' calc [translate cov%statecounty%]-ID = 0 aselect reselect SOURCE CN 'A' calc [translate cov%statecounty%]-ID = 1 aselect reselect SOURCE CN 'B' calc [translate cov%statecounty%]-ID = 2 aselect reselect SOURCE CN 'C' calc [translate cov%statecounty%]-ID = 3 aselect reselect SOURCE CN 'D' calc [translate cov%statecounty%]-ID = 4 aselect reselect SOURCE CN 'E' calc [translate cov%statecounty%]-ID = 5 aselect reselect SOURCE CN 'F' calc [translate cov%statecounty%]-ID = 6 aselect reselect SOURCE CN 'G' calc [translate cov%statecounty%]-ID = 7 q stop idedit cov%statecounty% line arcedit ec cov%statecounty% ef arcs select all unsplit save quit build cov%statecounty% line build cov%statecounty% poly tables select [translate cov%statecounty%].AAT calc [translate cov%statecounty%]-ID = [translate cov%statecounty%]# q stop idedit cov%statecounty% line kill geo%statecounty% all kill prj%statecounty% all kill gcl%statecounty% all &end &setvar cerr2 [close %fileunit%] &sys rm county.list &sys rm tigerfiles /* MAPJOIN the individual county coverages to form a full state coverage. &setvar covercount [filelist cov* covlist -cover -network] &setvar fileunit [open covlist ostat -r] mapjoin %state% net features &do i = 1 &to %covercount% &setvar cover [read %fileunit% rstat] %cover% &end end &sys rm covlist /* Set SOURCE codes equal to cover-ID so pseudonodes can be removed with /* UNSPLIT in ARCEDIT. tables select [translate %state%].AAT reselect SOURCE CN ' ' calc [translate %state%]-ID = 0 aselect reselect SOURCE CN 'A' calc [translate %state%]-ID = 1 aselect reselect SOURCE CN 'B' calc [translate %state%]-ID = 2 aselect reselect SOURCE CN 'C' calc [translate %state%]-ID = 3 aselect reselect SOURCE CN 'D' calc [translate %state%]-ID = 4 aselect reselect SOURCE CN 'E' calc [translate %state%]-ID = 5 aselect reselect SOURCE CN 'F' calc [translate %state%]-ID = 6 aselect reselect SOURCE CN 'G' calc [translate %state%]-ID = 7 q stop idedit %state% line arcedit ec %state% ef arcs select all unsplit save quit build %state% poly build %state% line /* Set cover-ID's back to equal cover#. tables select [translate %state%].AAT calc [translate %state%]-ID = [translate %state%]# q stop idedit %state% line /* Remove sliver polygons while retaining SOURCE codes. createlabels %state% 1001 build %state% poly pullitems [translate %state%].AAT PULL [translate %state%]-ID SOURCE END eliminate %state% el%state% # poly RESELECT [translate %state%]-ID > 1000 [unquote ' '] n n build el%state% line build el%state% poly kill %state% all rename el%state% %state% joinitem [translate %state%].AAT PULL [translate %state%].AAT ~ [translate %state%]-ID [translate %state%]-ID LINEAR tables $kill PULL q stop &return 3) Visually check the data for accuracy against the 1:2,000,000 county boundaries. When discrepancies occured, the data was checked against USGS 1:100,000 quad maps. 4) Add data from counties which were missing from the TIGER/line CDs or that could not be converted on the Data General. This was performed by several methods. Each method is followed by a list of counties by STATECTY code in which the data was inserted by that method. a) Missing or non-convertible counties which were completely surrounded by county boundaries that did convert had a label added to their blank polygon which was tagged with the appropriate STATECTY code. Missing Counties: Alabama: 01009, 01013, 01025, 01051, 01053, 01071, 01093, 01121, and 01125. Texas: 48105, 48107, 48109, 48155, 48157, 48159. Utah: 49019, 49027, 49033, 49045, 49053. Non-convertible Counties: California: 06001, 06017, 06025, 06049, 06095. Florida: 12105. Georgia: 13289, 13305. Louisiana: 22019, 22079, 22089. Maine: 23019. Minnesota: 27055, 27099. Nevada: 32031. New York: 36071. Texas: 48027, 48037, 48121, 48453. b) Non-convertible counties with a shoreline that were delineated by using the adjacent inland county boundaries and a shoreline obtained from the USGS 1:2,000,000 data set with a buffer to match the buffer of the adjacent Census shoreline. The shorelines of these counties have a SOURCE code in the .AAT file of 'X'. Alabama: 01097. California: 06037, 06073. Florida: 12009, 12071, 12099. Georgia: 13051. Louisiana: 22075. North Carolina: 37053. South Carolina: 45019. Texas: 48167, 48245, 48261. c) The following county boudaries were obtained by processing Census TIGER/line files obtained from the U.S. Environmental Protection Agency (The same procedures were used on this data): Alabama: 01027, 01035, 01037, 01059, 01073, 01095, 01099, 01115, 01123, 01129, 01133. Texas: 48101, 48103, 48153. Utah: 49023, 49025, 49037, 49043, 49047. d) The following county boudaries were obtained by processing Census TIGER/line files on an IBM RS6000: Florida: 12105. South Carolina: 45053. Texas: 48253.
Reviews_Applied: Post-processing data review performed as mentioned above by Mark Negri. Data Modifications by USDA Forest Service Staff: Sept. & Oct.-2000: The coverages were downloaded by USDA Forest Service personnel on 22-Sep-2000 in compressed Arc Info Export format along with their associated metadata. The coverages were then reprojected to match Assessment standard Albers using the Arc Info PROJECT command, the items were adjusted to one record per county or municipality, and sliver polygons were removed. The coverage was then subsetted to the thirteen Southern states of the Assessment using Arc View's Theme Query tool and state FIPS code, then exported as shapefiles.
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