[GIS] Adding census tracts to addresses using ArcGIS for Desktop

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I am as rookie as they come in this space. I have a large list of addresses and longitude latitude points for different locations within a state. What is the easiest and most efficient way to determine the respective census tract number for each address? Over 50,000 addresses and I just want to pull in the tract into excel for each

Right now it is just one single data set. I can manually look up the address in some third party systems, but that process is extremely inefficient. I also don't know how to use arc gis but I've tried valiantly to import the data points into the map, then layer the census tract map over that. Unfortunately, I don't know if there is a way to merge those two sets of data then export from ArcGIS back into the spreadsheet?

Best Answer

If you have both layers in ArcGIS, use the spatial join tool to capture the census tract attribute to each address point. The address point will be the 'Target Features' and the census tracts will be the 'Join Features'. Use the 'JOIN_ONE_TO_ONE' Join Operation.

This will output a feature class of the addresses including the attributes from the census tracts.

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[GIS] Automatically creating 2D-point features for ArcGIS Desktop from addresses in SQL database

What information is in the sql-table? Are you saying it is a sql spatial table or just a listing of building names with addresses?

if just addresses you would need to use the geocoding tool in arcmap.

(ver9.3.x) Under the tools pulldown select geocoding

(ver10) select the geocoding toolbar. This will create a special point file with all the records in your address list with a code indicating whether the address geocoded correctly (or not).

BTW you may need to parse the addresses into seperate fields or use the complete address with the appropriate geocoder.

You can read more about geocoding in the arcmap help search >geocoding
if the data contains x-y information you can simply add the table to arcmap> right click on the table and select Display XY Data. You would then select the coordinate system your data is in (usually going to be [geographic system WGS84]) lat lon.

[GIS] Mean Center/Median Center tool providing points mathematically centered but physically appearing in the wrong location

Census tracts assume/present a uniform population density. If you are using Mean/Median Center on each tract, you're essentially calculating the centroid or geographic center of the tract. That centroid may or may not actually fall within the shape, particularly in the case of non-rectangular bounded shapes, such as 'C' (like your example image) and 'L' shapes, or shapes with holes in them.

If you only seek to get a point within each tract and be sure that it falls within the tract, Feature to Point will allow you to do that but it requires an Advanced license. Without an Advanced license, you could add x and y attribute fields, calculate those geometry properties to those fields, then create an xy event layer out of those values to get points (but again these may or may not fall within the boundary). If you are comfortable using python you can use a script to create a 'label point' (or 'inside centroid') using arcpy geometry objects, as follows:

# create points list
points = []
# get spatial reference from polygon feature class
sr = arcpy.Describe("shapes").spatialReference
# loop through polygon feature class
with arcpy.da.SearchCursor("shapes","SHAPE@",spatial_reference=sr) as cursor:
    for row in cursor:
        # add centroids to points list
        points.append(arcpy.PointGeometry(row[0].centroid))
# write points to disk
arcpy.CopyFeatures_management(points,r'in_memory\centroids')

Proper use of the Mean/Median Center tools would be to select all or a group of census tracts and use the population value as a weight field. This would then produce a single point at the geographic population center for those selected tracts (not one point per tract). I'm unclear on what you mean by 'create population weights', so I don't fully understand what you are trying to accomplish.

Best Answer

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[GIS] Mean Center/Median Center tool providing points mathematically centered but physically appearing in the wrong location

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