# Joining data on congressional districts

**URL:** https://forum.ipums.org/t/joining-data-on-congressional-districts/3670
**Category:** General
**Created:** [July 28, 2020, 8:26pm UTC](https://forum.ipums.org/t/joining-data-on-congressional-districts/3670 "2020-07-28T20:26:10Z")
**Posts on this page:** 1
**Showing post:** 7

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### Author: ![MPC\_vanriper](https://avatars.discourse-cdn.com/v4/letter/m/bc8723/32.png) [@MPC\_vanriper](https://forum.ipums.org/u/MPC_vanriper)
#### Post date: [July 29, 2020, 3:33pm UTC](https://forum.ipums.org/t/joining-data-on-congressional-districts/3670/7 "2020-07-29T15:33:54Z")

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Unfortunately, it is not a straightforward process to conduct the process if you’re not familiar with geospatial software. The basic outline is:

1. Obtain 51 census block shapefiles from 2000
2. Obtain the CD and ZCTA shapefiles
3. Merge them into a nationwide file
4. Convert the blocks to centroids
5. Overlay the centroids on the CD shapefile
6. Overlay the centroids on the ZCTA shapefile
7. Merge the results of (4) and (5) into a single data file
8. Merge the results of (6) with the 2000 census block populations
9. Roll up (8) by unique combinations of ZCTA and CD codes

You would also be handling large files because there were ~7 million census blocks in 2000.

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