Mark Rober did a fairly scientific self-run experiment where he sent 200 wallets around the country to be dropped in various cities then collect data on who returned them (if possible). He controlled for age, big cities vs small city size, gender, poor/rich, etc.

Summary: 2/3 of the wallets were returned, and of those 96% still had the money inside. He got lots of other interesting data, but I thought his summary was the most impressive:

Lately it seems like so much of what you see online is meant to stoke outrage at some group of people versus ourselves because that’s what gets shared. That begins to warp our perception that the only good people out there are those within our own group. But this data shows that across any age or gender or socio-economic background, across the whole religious spectrum through middle America and along the coast there are lots of good people everywhere.

Not only that, but they constitute a [very clear] MAJORITY. They didn’t call for some reward or Facebook likes or because they knew someone was watching. They did it because it was simply the right thing to do and I think that’s pretty cool and something worth remembering.

Things that didn’t seem to make a difference:

• Gender – pretty much equal return rate after slightly method change.
• Rich or poor areas – same return rate
• Age – average age of person that returned the wallet was 36, which is pretty much the average age in the US. (Would be interesting to dig into the average age of persons who walk in these areas vs driving/etc. Old people probably don’t walk as much, kids under 7 probably don’t walk alone either. But I agree this is probably a fair representation.)
• Religious* – 60% were returned by people who were religious vs 40% who were not. This largely matches the average city population, so he didn’t consider it statistically meaningful.

Things that did make a difference to at least some degree:

• Small cities averaged better return rates than big cities
• City itself – huge difference

Here’s the city results in order from best to worst:

• Perfect (10/10 returns): Chicago, Salt Lake City
• Good (9-7 returns): Nashua, ID, Hill City, SD, Portland, Parma, ID, Las Vegas
• Middle (7-5 returned): San Francisco, Winnipeg, Washington DC, Huntsville, New London, Seattle, Los Angeles, Miami, Dallas, Edmonton
• Worst cities for return rate (4 or under): Detroit and NYC