Hello. I’m using NHGIS Census Tract (and Block Group) GIS files for 1990, 2000, and 2010. In the 2000 and 2010 files, there are ALAND and AWATER variables to distinguish water from land area within a given CT or BG. In the 1990 files I have only seen SHAPE_AREA variables. I’m not sure if SHAPE_AREA is the total area for water+land, or if there are separate water and land area variables available for 1990.
Basically, I need to have a variable for area across all years that uses a consistent method so it is comparable, and I would prefer to use the land area variable if available across those 3 years. Can anyone provide clarity for this for 1990 or know where I can find documentation about this? Thank you!