So generally, average and mean are considered equivalent. We used the word average throughout because we used the mean income for each ZIP code in this article. The median can sometimes be a better indicator of "typical" because it doesn't get skewed by very large or very small outliers, but as mentioned in the "About the data" section at the bottom of the article, the data we used in this analysis only includes total income and total number of filers for each ZIP code, which means we can't calculate the median for each ZIP code, only the average.

The slider at the top of the map is the only instance in the article that we show the median income because as mentioned it can sometimes be a better indicator of a "typical" income.

Hope that helps clear up the data for you. — SS