Dear NHGIS team, I seem to remember that you were working on creating GIS boundary files for 1970 places. Is that correct? If so is there a timeline available. Alternatively, will the forthcoming 1970 block geography have the ID to aggregate to Place level?
A side note on 1980 boundaries. Your interactive map viewer appears to show 2010 boundaries for the 1980 decade.
Many thanks!
As you may know, NHGIS provides 1970 place point files, but at this time, we have no plans to create boundary files for 1970 places. We still plan to add 1970 block boundaries at some point, but we can only provide those for areas where 1970 blocks were defined, which excludes most smaller places.
I also don’t know yet if we’ll include any place IDs in the 1970 block data. I imagine those could be very useful, but it’s unfortunately not as simple as in later years. Before 1990, census blocks did not necessarily nest within place boundaries. Where a block straddles a place boundary, we wouldn’t be able to identify a single corresponding place, and it wouldn’t be possible to generate place data by simply aggregating block data.
Thanks for alerting us about the incorrect 1980 block boundaries in the interactive map. We hope to correct that soon!
“Before 1990, census blocks did not necessarily nest within place boundaries.” Very good to know!
Thank you for the comprehensive and prompt answer.
I realize that NHGIS has not had a chance to digitize block files from 1970, but do you have access to 1970 block maps? I am working on my dissertation on Omaha/Douglas County, Nebraska, using block maps from each decade, while I have been able to find and digitize 1950 and 1960, I cannot find physical or pdf. block maps from 1970. I was wondering whether you have access to these maps, or a way to procure them. I have contacted Omaha Public Libraries and they do not have copies of them. Thank you.
The libraries of our home institution, the University of Minnesota, have a complete collection of 1970 block maps (as far as we can tell). Do the Omaha libraries participate in Interlibrary Loan (ILL)? As it happens, our libraries have complete 1980 block maps only on microfiche, which is a very cumbersome format for our work digitizing 1980 blocks, so to avoid using that, we’ve worked with libraries around the country to acquire 1980 paper maps (hard copy or scanned). We initially used ILL for that, and then, more efficiently, worked through a network of Government Documents librarians. I’d recommend inquiring with your library to see if they could get a loan of 1970 block maps from another library. Let us know if that doesn’t work out. We plan to start preliminary work on 1970 block creation in the coming months, and we could prioritize Omaha.
I was able to check with the University of Nebraska at Omaha (I go to the Lincoln branch) and was able to get them. I plan to digitize them, within the next few weeks. I am not sure whether you are interested, but if you want copies of my shapefiles, I have Omaha completed for 1950 and 1960, and will work on 1970. I know how long it takes to complete these, so if this would help IPUMS, I would love to share. I am just glad that you have completed 1980.
Thank you,
I’m glad to hear you were able to get them. We don’t have any current plans to create block bound boundaries for 1960 or 1950, so I’ll decline your offer to share them right now, but thanks for letting us know about them. We’ll keep it in mind if we ever do have need for older boundaries. We’ll probably use our own process to construct 1970 block boundaries for Omaha (for consistency and quality assurance), but if you’d like to share your version when you’ve completed them, please do. (You could email nhgis@umn.edu.) I’m sure that’d be helpful for us for reference and verification. Thanks!