Dear Yeonhwa,
This is actually more complicated than it seems, and it’s going to require some research to track down each decade’s central cities. You’ll also have to do some custom programming to identify the census tracts in central cities.
The concept of the central city was first introduced in 1950, when standard metropolitan areas (SMAs) were first developed by the Census Bureau. I found a PDF listing central cities in 1960 and 1950, and I recommend looking in it for a list of central cities used for those two decades.
Then, once you’ve deteremined the central cities for those decades, you should download census tract CSVs from NHGIS. Then, you can use the values in the AREANAME to identify the tracts that fall within central cities. For example, two census tracts in Alameda County, CA, in 1950 were
STCTY-06001 TRACT- 0072 IN OAKLAND CA
STCTY-06001 TRACT- AC 0001 IN ALBANY CA
The first record is in Oakland, which was a central city in 1950. The second record is also in Alameda county, but was in Albany, which was not a central city in 1950. You’ll have to do some string parsing to flag tracts in the central cities.
In 1960, you can adopt the same strategy. I will also point out that the 1960 tract file has a PLACE field containing codes for cities. I would bet that most tracts with a value in the PLACE field are likely to be inside central cities.
In 1970, you can get a list of central cities in NHGIS in the 1970_Cnt4Pa. Central cities are a compound geographic level in 1970. You can also central cities for each standard metropolitan statistical area in this PDF. Unfortunately, the 1970 tract data do not have a city code on them, which would facilitate their identification as central city tracts. By 1970, census tracts do not always nest within cities, so there is not as clean a way to identify tracts within central cities.
In 1980, you will need a compound geographic level to identify tracts within central cities:
Census Tract/Block Numbering Area (by State--Standard Metropolitan Statistical Area--County--County Subdivision--Place) - tract_02098
This geographic level is available in the 1980_STF1 dataset. If you download this file, you will want to filter for census tracts with a value of PLACEDESC == 3. I believe these represent tracts within central cities of SMSAs.
In 1990, you will need a compound geographic level to identify tracts within central cities:
Census Tract (by State--County--County Subdivision--Place/Remainder) - tract_080
This geographic level is available in the 1990_STF1 dataset. If you download this file, you will want to filter for census tracts with a value of PLACEDESC == 3. I believe these represent tracts within central cities of SMSAs. You can also get a list of central cities from the following geographic level:
Central City (by Metropolitan Statistical Area/Consolidated Metropolitan Statistical Area--State) - place_382
I recommend cross-checking the tracts with PLACEDESC == 3 against the list of central cities in the place_382 file.
I think the 1970 identification will be the most difficult since the geographic detail in the summary files is less than in later years.
Sincerely,
Dave Van Riper
IPUMS