TL;DR Question: I want to calculate distance from point to edge of nearest polygon for 2,000 points in Continental United States. What is the best projection to use?

Full Question: I have two datasets. First, I have long/lat data for the point of origin of ~2,000 wildfires in the United States. Second, I have a shapefile for Census Designated Places (created by merging shapefiles for individual states from the US Census' website: https://www.census.gov/geo/maps-data/data/cbf/cbf_place.html).

I want to calculate the distance from each of these fires to the edge of the nearest Census Designated Place. Typically, I believe that I would do this using "Generate Near Table" in the ArcToolbox. However, the Census Designated Places shapefile uses a geographic coordinate system (GCS_North_American_1983). So I think I need to change the coordinate system to one that allows me to correctly estimate distance. Unfortunately, I don't know which is the best projection to use.

Would USA Contiguous Equidistant Conic be a safe choice for calculating distances for so many points spread across such a large area?

  • 1
    When using the Near tools, choose the geodesic method. Then the coordinate system won't matter.
    – mkennedy
    Nov 16, 2015 at 19:01

2 Answers 2


Within the the Generate Near Table (Analysis) tool select GEODESIC as your method.

This finds the shortest line along the ellipsoid surface of the earth rather than the planar surface of a projection. This is appropriate when working with large areas like the entire continental US.

ArcGIS Resource and Image Source enter image description here


If you are generally interested in projecting data and make it look accurate and measurable through a ruler, you are suggested to you an equidistance projection. Your projection there works just fine. But if you want to use WGS web Mercator, you can need to calculate the geodesic distance to get the actual distance within a equidistance projection.


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