But, while some theories help explain a small portion of the map, there hasn't been any theory to completely account for why people in some states give and those in others don't.
First, the map:
The most obvious outlier is also the easiest to explain: Utah, with a 10.6% charitable giving rate, is far and away the most generous state in the union. It also has the highest proportion of members of the Church of Jesus Christ of Latter Day Saints in the union. (More than half the population self-identifies as Mormon, according to the Pew Forum on Religion & Public Life.) The church's tithing requirement, in which members are expected to donate 10 percent of their income, goes a long way toward explaining Utah's impressive generosity.
This factor also may also help explain the relatively high generosity of at least one other state: Idaho has a very high percentage of LDS members -- and also ranks among the 10 most generous states.
Another angle might be unionization: All but one of the most generous states also have right-to-work (anti-union) policies; Nine of the 10 least generous states don't. Geography also seems to play a part: Eight of the 10 most generous states -- Maryland, Tennessee, South Carolina, Georgia, Alabama, Mississippi, Arkansas and Oklahoma -- are located south of the Mason-Dixon Line. All eight of the least generous were in the North.
Ultimately, though, Utah may give the best glimpse into the way that charity works in America. Early in 2012, Gallup released a poll ranking the most religious and least religious states in the union. Of the most religious, only two -- Louisiana and North Carolina -- were not among the most generous. Conversely, of the 10 least religious, five were among the least generous.
In other words, when it comes to giving to others, it looks like the shortest way to an American's heart may be through the collection plate.
Bruce Watson is a senior features writer for DailyFinance. You can reach him by e-mail at firstname.lastname@example.org, or follow him on Twitter at @bruce1971.