Which county is the most charitable in Tennessee?

The latest round of charitable contribution statistics, as well as a wide range of other useful data generated from 2017 tax returns, are now available from the IRS Statistics of Income (SOI) program. This annual data set is extremely useful for academic purposes, including studies of income inequality, concentration of wealth, and tax incidence. But there are also important practical uses, especially for non-profits and others engaged in fundraising. Zip code data is available, which can be used to target areas where taxpaying households are reporting greater levels of charitable giving (data is also available for states, metro/micro areas, counties, and congressional districts).

Here's a summary of charitable contributions for Tennessee's largest counties:

Summary data can be calculated in several ways. Here I've ranked large counties (100,000+ in population) by the share of tax returns reporting deductions for charitable contributions. For example, 38.1% of taxpaying households in Williamson County reported deductions for charitable contributions in 2017, which is by far the highest rate among all counties in TN and more than twice the statewide rate (16.8%). That shouldn't be too surprising given the median household income in Williamson County of $103,543, which is also, by far, highest among counties in the state (Wilson is second highest at $66,123). Charitable contributions, calculated as a share of tax returns (.85) or as a share of total income (.53), and household income are positively correlated, as you might expect.

Here's a look at which counties of any size exceed the statewide rate (16.8%) of tax returns with charitable contributions:

I've bolded two smaller counties, Fayette and Loudon, that join many of the largest counties in the state on this list. Fayette County, in particular, stands out at 25.8%, the second highest share of taxpaying households reporting charitable contributions.

Same idea here, but ranked by charitable contributions as a share of total income:

Shelby County tops this list at 3.6%, compared to the statewide rate of 2.4%. In other words, deductions for charitable contributions reported by taxpaying households in Shelby County in 2017 were equivalent to 3.6% of total income reported.

Finally, statistics are also available by income bracket. Here's a look at counties that exceed the statewide rate (75.5%) of returns reporting charitable contributions among households with $200,000 or more in total income reported:

Shelby County tops that list at 82.4%, slightly ahead of Williamson County. Shelby County also ranks highly on charitable contributions as a share of total income among $200,000+ households that exceed the statewide rate of 3.7%:

Of course, not all charitable contributions (or income) are reported on tax returns. Further, tax deductions do not adequately reflect all charitable activity performed by residents of a community. Significant contributions are made in non-monetary ways.

That said, which county is the most charitable in Tennessee, based on this newly published data for 2017? I'm giving the nod to Shelby County, but its highest-income households need to step it up a bit to catch Hamilton. My second overall goes to Williamson, but I'm curious about its absence from that last table on high-income giving.