The continental United States has vast flat plains and long mountain ranges. But what do people experience? They don’t live at the the extreme highest and lowest elevations. One way to answer this question is find the average elevation of the population of the USA. We can approximate the answer by doing the following:

  1. Calculate the mean elevation of each county based on the elevations of a set of populated places in each county
  2. Get the population of each county
  3. Calculate a weighted mean elevation for the country based on the above


1. Calculate mean elevation of each county

We can approximate the mean elevation of each county using the ‘populated places’ data set from the USGS Populated Places topical gazetteer from GNIS. Most counties have more than 10 populated places, and we can average them to get an approximation for the mean elevation of the county.

Example data from USGS ‘Populated Places’ data set with calculated mean elevation per county
state_alpha state_numeric county_name county_numeric n_poplulated_places mean_elev_in_m mean_elev_in_ft
IA 19 Carroll 027 21 391 1284
IN 18 Fayette 041 16 285 935
KY 21 Kenton 117 63 214 701
NE 31 Dawes 045 14 1114 3654
NE 31 Deuel 049 5 1091 3579
TX 48 Ellis 139 55 163 533
TX 48 Hill 217 43 194 638
TX 48 Hunt 231 52 163 535
TX 48 Navarro 349 51 130 427
VA 51 Buckingham 029 52 151 495



2. Get population by county

I downloaded county-level population estimates from ACS 2014-2018 via the Census Bureau’s Planning Database at https://www.census.gov/topics/research/guidance/planning-databases.2020.html



3. The answer

The average elevation of the population of the USA is 856 ft, which is a weighted mean based on county population. Compare that to the simple average of county elevation: 1302 ft. It seems reasonable to me that weighted mean is lower elevation than the simple mean, since there are more people near the coasts in higher-density counties than in the middle of the country and in mountainous areas.

Note that counties in Alaska and Hawaii were included when calculating the mean, however they are not included in the plot below.



Most people live in the green counties (below 1000 ft elevation).




Three states (AZ, CA, CO) have a range of more than a mile in elevation between the lowest and highest mean county elevations.



4. Notes

Can we rely on the population mean elevation calculated based on “populated places?” Yes, because (1) 94% of the counties have more than 10 populated places ; and (2) those with less are mostly sparsely populated ranching and farming areas in a band from Texas to North Dakota where it’s relatively flat.





By Daniel Moul (heydanielmoul via gmail)

CC-BY This work is licensed under a Creative Commons Attribution 4.0 International License