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I'm incredibly new to creating these types of maps, but I'm trying to create a coverage map not unlike the cell companies show their coverage. Our database simply has lists of ZIP codes that our service covers and I want to display these on a map, colored in, like the cell phone companies do.

I have figured out how to do this on my own (using QGIS and joining my CSV list with the shapefile from the USPS of zip codes)... But the thing I can't figure out how to do is to show a radius around each zip coded area. Our coverage extends 100 miles (50 miles in each direction) from the center point of each zip code.

With a list of over 32,000 zip codes, is there a way to easily extend the coloring area around each zip code to include this extra area?

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"show a radius around each zip coded area. Our coverage extends 100 miles (50 miles in each direction) from the center point of each zip code."

  1. Convert your Zip Codes to Centroids. Vector - Geometry Tools - Polygon Centroids.

Centroids

  1. Buffer the Points. Vector - Geometry Tools - Buffer

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Some things to consider.

Use a projected coordinate system that is in meters then your buffer distance will be 885139 meters. I would suggest SR-ORG:7301 as you are working in the USA and desire a unit that is stable (ie not degrees).

  • Awesome, thanks! The only problem I'm having is that it seems to be basing the centroids data off the source USPS file, not what is "joined" from my CSV.... is there a way to export my new joined data out as a new shape file? – Mike Stecker Jan 6 '16 at 18:17
  • sure, just delete the fields you have a 0 or nodata in your joined field and run it on this subset. You can also just select the ones you want to run it on in the buffer tool. – If you do not know- just GIS Jan 6 '16 at 18:25
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Once you've done your join, right-click the joined polygon layer and 'Save as' and create a new shapefile containing all the joined data. (note: here you can change the coordinate system as you save to the new file)

Then Use the Vector > Geometry Tools > Polygon centroids to turn all your zip code polygons to points

Then use Vector > Geoprocessing > Buffer to buffer your points by 50mi

But - you'll have to make sure your zip code polygons (or points) are in a coordinate system that is in FEET so when you use the buffer tool

So - what area do your zip codes cover?

  • Awesome, thanks! The only problem I'm having is that it seems to be basing the centroids data off the source USPS file, not what is "joined" from my CSV.... is there a way to export my new joined data out as a new shape file? The zip codes cover just about all 50 states – Mike Stecker Jan 6 '16 at 18:20
  • @MikeStecker great! I just added a step to the beginning of my answer for saving out to a new file and re-projecting as you go... let me know if you have any more issues... – DPSSpatial Jan 6 '16 at 19:18
  • Just curious why feet? – If you do not know- just GIS Jan 6 '16 at 21:50
  • he said he wanted to do buffer in Miles... – DPSSpatial Jan 6 '16 at 22:09

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