Can you provide an easy-to-understand definition for the columns orig_are, shape_leng, and shape_area on the GIS files for the 1930-2000 Tract (Tiger 2008).
Can you also provide a definition for area_uncli?
The problem that I am having is that for each State - County I get multiple Tract numbers (see table below) and the only columns that could differentiate between them are those previously mentioned. But I do not know what they mean.
decade | statenam | nhgisnam | tract | orig_area | shape_leng | shape_area
1930 | California | Los Angeles | 100 | 59888907.27 | 42526.95182 | 59808492.52
1930 | California | Los Angeles | 200 | 42863501.55 | 31753.07723 | 42826617.37
What I eventually want to do with this information is to identify a city or a county subdivision, or latitude/longitude coordinates, or zipcodes. Is that even possible?
I read the answer on a previous topic about the unit of shape_area and shape_leng, but can you be more specific? Can I use the center point of the Shape Area to get latitude/longitude? If that is possible, Do you know a particular software that does that kind of transformation (can it be done with PostGIS)?
I also noticed that tract numbers are reused for each State - County pair (100, 200, etc), and the shape_area, orig_are, and shape_leng are the same for each Tract. That tells me that most likely I will not be able to get the lat/lon from those columns, but if that is true, perhaps do you know another way to get lat/lon, or county subdivisions, or zipcodes for 1930-2000 Tracts.
Any help on this would be greatly appreciated. Thank you!