Basic questions about digital block geometry for 1980 to 2000 for US territories

NHGIS
1

I have been using the census block shapefiles and tables for 1990, 2000, and 2010 available from NHGIS without really understanding what was going on, because NHGIS makes it so easy. NHGIS even offers a choice of shapefiles for 2000 because Census provided to versions based on different methods. I’ve assumed that for whatever reason, the blocks for 1980 and before were not digitized and hence NHGIS cannot provide it.

I was not clear on why blocks for the territories do not show up on the list. I assumed that either Census did not create all the data, budget limitations forced omission, or a Caribbean initiative elsewhere did it.

Now I am trying to get the same data for Puerto Rico, and possibly other territories. So I probably need to finally understand what is really going on. Perhaps I need to duplicate for PR what NHGIS did for the states, or perhaps it is impossible. Or maybe someone else did it. I am hoping you can fill in the gaps in sources and my understanding.

I downloaded without issue the TIGER shapefiles for 2000 and 2010 that Census offers at https://www.census.gov/geographies/mapping-files/time-series/geo/tiger-line-file.2000.html . Census claims that I will be able to find the tables to associate at data-dot-census-dot-gov I expect that joining those tables will be a bit more tine-consuming as it lacks your GISJOIN field; but not too bad once I find the tables comparable to the csv files NHGIS provides.

But what really stumped me concerns the 1990 blocks and—while less important—the blocks for 2000 using the 1990 approach. There is a statement that Census 2000 is available in both formats, which looks promising. But when I downloaded the files from https-www2-dot-census-dot gov/geo/tiger/tiger2k/, the format is not anything that ArcGIS10 or ArcGIS pro recognize. For 1992 Census warns

The 1992 TIGER/Line Files serve as a link between 1980 and 1990 geography. These files are in an early TIGER/Line format that generally does not work with shapefile conversion software….Technical support is not available for these files.

My guess is that 1992 is the vintage of the digital product for 1990 blocks. A cursory web search suggests that others have been stumped by this obsolete format. Should I infer that NHGIS managed to read those same files and convert them to shapefiles? The discussion of similar issues at GIS Files | IPUMS NHGIS does not delve into this in detail, so I am wondering whether the difficulty of doing so is one reason why NHGIS did not do so for Puerto Rico. If this is really time-consuming, I can just drop the matter as impractical, but I wanted to check with people who would know.

In addition, can you shed light on the statement by Census that the 1992 provides a link to 1980 geography? Does this mean that there is a digital product for the 1980 blocks as well which, to date, simply has not been converted to a format that most people can use?

Thanks
Jim

2

Hi Jim,

First, to explain the absence of Puerto Rico data in NHGIS for 2000 and earlier…
Most of the NHGIS data for this period was added during the initial 5-year NHGIS grant (2001-2006), when we were adding a huge variety of historical resources stretching back to 1790. I think the main reason we omitted Puerto Rico then was that most older historical datasets omitted Puerto Rico, and for the later years when it was available, the team probably continued omitting Puerto Rico because its data could have various limitations and deviations from other US data, which would add integration and design costs that we couldn’t fit in at that time.

To my knowledge, Puerto Rico data from the 2000 census (and possibly from some earlier years) is organized exactly as are the data for the rest of the U.S., so it’s apparent now that adding Puerto Rico for 2000 would not have added much cost back then, but it would be a significant cost to go back and do that work now. It’s been difficult for us to prioritize that work over many other initiatives, but we still hope to do it someday! Meanwhile, we have included Puerto Rico in all our later data additions (the 2010 Census and ACS) and will continue to do so.

As for other territories besides Puerto Rico, the Census Bureau does produce some data products for these areas, but these are generally not part of their standard products, so it would be more costly to integrate them into our system than Puerto Rico.

Sources of 2000, 1990 & 1980 block boundary data for Puerto Rico
When we created 2000 NHGIS shapefiles from the 2010 TIGER/Line files, we included Puerto Rico in our work, but we chose to exclude the final Puerto Rico boundaries from the NHGIS site because we don’t have any 2000 summary tables to join with them. It’s become apparent (in part because of your question!) that those boundaries can be useful even if we don’t provide corresponding tables. I’ve now posted our 2000 block boundaries for Puerto Rico (based on 2010 TIGER/Line) on our server, and you can download them through this link. We’ll also plan to release them through our site in a future update.

Unfortunately, to my knowledge, we’ve never yet derived Puerto Rico block boundaries from the 2000 TIGER/Line files for either the 2000 or 1990 census blocks.

The 1992 TIGER/Line files do include 1990 and 1980 block boundaries, but the 1980 block definitions are badly incomplete. All throughout the country, many of the blocks–around a quarter–that appear in 1980 summary files do not appear in the 1992 TIGER files. For that reason, we have a major project now underway to construct polygons for most of the 1980 blocks that are missing in the 1992 TIGER. We plan to release the new data over the next few years, starting sometime later this year.

There are some tools for importing data from 2000 and 1992 TIGER/Line files using either ArcGIS or QGIS, so if you have one of those software packages, you should be able to extract 2000 and 1990 block boundaries for Puerto Rico. In ArcGIS, you should be able to use the Quick Import Tool, though it requires the “Data Interoperability Extension.” You can also use the Add Vector tool in QGIS. That said, there are some unavoidable complexities to working with the older TIGER/Line files, and you may find it’s not worthwhile to figure those out, but it depends on your needs and available time!