Census Data

Problem:

Create a Thematic Map using any attribute.

I need to find out Total Population distribution of Wake County of North Carolina.

In order to solve the problem, first I downloaded Tabular Data from American Fact Finder >Advanced Search>Geography>Census Tract-140>North Carolina>Wake County>Age and Sex. Zip file. I got one metadata file and one .csv file. Then I downloaded from Tiger Line Shape file of 2010 Census Tract of Wake County,North Carolina.

The Table I used named ACS_15_5YR_50101_with_ann.csv

I need to use the attribute HCO1_EST_VCO1 for Total Estimate-Total Population in Tabular data.

I downloaded the Tiger Line shape file named tl_2010_37183_tract10.shp.

Analysis Procedure:

I need to review the metadata first that for which attribute or table I am going to make a Thematic map. After opening the .csv. file in Excel, I need to make an xls file and edit the data in Excel for adding the tabular data in Arc Map. I need to add the shape file in Arc Map as well. Then I need to make a spatial join the shape file or county tracts layer with the tabular data on a common field. In order to make a common field, I need to add a field in county tracts layer and make a similar field with same value resembling the tabular field with identical value, because both values in both common field should be identical, then join can be established. Therefore, I used certain approach following certain parameter by adding an ID field as text(string) field and as a short integer and precession of 15 in shape file or Tract layer and used field calculator with VB script syntax and Int () function for this purpose. Then I need to ensure that values match in the new field/column type and Geoid2 field in tabular data. After successful join I can make a thematic map for one attribute of our choice by using symbology from layer properties.

In order to find out the Population distribution in Census tracts of Wake County, North Carolina, I reviewed the metadata of tabular Age and Sex data and csv file in Excel. Before editing csv file, it needs to be saved as Excel 97-2003 Workbook file2003.The tabular data may need to be edited to work properly in ArcGIS. The table should have unique field names which are not supposed to contain any special characters and the associated attributes. ArcGIS may truncate the long field names to 15 characters too.  I edited by keeping only 8 characters for a certain field. The descriptive attribute rows had to be deleted.

In Arc Map, the shape file had been added and XLs file had been added respectively. In order to visualize the population distribution, the tabular data must be spatially joined with shape file or Tract layer. But there is a need to make a common field, since there was no common field seen. Otherwise join will not be resulted. In this case I took an approach following certain parameter to add an ID field as text(string) field with a short integer field type and precession of 15 named STFID2 in Tract Layer or shape file. Then I used Field Calculator to convert in VB script syntax and Int([ GEOID10]) function, as both resembled same value, but ID name needed to be changed into STFID2 to meet the same criteria of common field name of GEOid2 in tabular attribute data. As FID is used in shape file for feature class, but OID or Oid is used for object in table. Both represent unique identifier of an object or feature class.

Therefore, spatial join had been accomplished for the Tract layer or shape file with the table based on common field of STFID2 and GEOid2 and after reviewing the join by using the attribute HCO1_EST_VCO1 for Total Estimate-Total Population, the map had been symbolized with graduated color representing lowest to highest populated census tracts of Wake County.

                                  Workflow Diagram

Results:

Application and Reflection:

I made a lot of Thematic Maps before, as I worked in a Thematic Mapping Organization, I know that any kind of Thematic map making is not possible without spatial join. But ID matching is the key factor for the visualization of map as well as recorded value in the field or attribute.

I would like to make a Thematic map about Asian Race population distribution for block groups in Wake County, North Carolina in 2010.

I downloaded the Race Table for block group in Wake County, NC from American Fact Finder Website. Then I downloaded block group of Wake County, NC shape file from Tiger Line Shape layer of Census Data.

After converting the table into xls file, I edited the data deleting dots and extra letters from the fields as well as one descriptive rows, then I added shape file and xls file in Arc Map.

Using similar approach by adding an ID field in shape file or Block group layer, I was able to join with the table based on the common field name with common numeric value, successfully joined the shape file and tabular data. Then I made a thematic map symbolizing the attribute/field about Total Asian Population and it visualized the distribution of Asian Population over Wake County. I found largest Asian population lived in western part of Wake County in 2010.

In this way we can make any thematic map regarding population distribution of US and Puerto Rico.

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