Good morning Hank, it's Tuesday.

So what if I told you that for Americans a single data point can affect your life expectancy more than whether you smoke, more than if you get an annual physical, or whether you exercise regularly. That data point is your zip code, the 5 digit number the U.S. Postal service uses to deliver your mail.

 In the U. S., your zip code can affect your life expectancy by 20 years, and according to some recent research, the gap between the healthiest communities and the sickest ones is getting bigger.

So I live in the city of Indianapolis, and in my zip code, the life expectancy is around 80, which is slightly higher than the U.S. average, but if you live 3 miles north of my house, the life expectancy rises to 83.7 and if you live 3 miles south it falls to 69.4.

Now, maybe that doesn't seem like a big deal to you, but just to put it in some context, on average, non-smokers in the US live about 10 years longer than smokers.  People who exercise regularly live about 4.5 years longer than those who don't, and whether you live three miles north or south of my house affects your life expectancy by 14 years.  

Wait, slight tangent, am I gonna spend all of those 4.5 years exercising.  I have to do some math.  Okay, so assuming 2.5 hours of moderate intensity exercise per week beginning at the age of 16, you're gonna spend about 1 of your extra years exercising.  Then you're gonna spend another 1.5 years sleeping.  You basically get 2 extra years, except, of course, that's not how life expectancy works.

If you, a particular individual, exercise, it doesn't mean that your particular life will be increased by 4.5 extra years or even 4.5 extra hours, it just means that on average, that's what happens.  Similarly, living in a particular zip code doesn't mean a particular fate for individuals but on average, geography has a huge impact on American health and longevity.  So what's causing that profound life expectancy gap?  Well, as usual, it's complicated.  Like, the eastern Kentucky communities where life expectancy is under 70 have higher rates of tobacco usage than the central Colorado communities were life expectancy is over 85, but eastern Kentucky is also poorer and has fewer doctors.  

Communities with low life expectancy tend to have less access to healthy food and more uninsured people.  People in those communities are also more likely to have certain chronic health problems like diabetes and hypertension, whereas the people in the healthiest communities tend to be, you know, rich and have excellent access to healthcare, and the zip codes with the highest life expectancy also tend to be in places where there's lots of physical activity, like ski resorts in Colorado or wealthy beach towns in California.  

Now, I know to many of us, this is not surprising.  Like, we take it for granted that rich people will have dramatically longer and healthier lives than poor people, but increasing inequality of life expectancy within countries is not actually the norm.  In fact, while life expectancy variability has been rising within the US steadily since 1980, in most other rich countries, it's been declining.  Canada, for instance, has seen a significant decline which is one of the main reasons why Canada's overall life expectancy is higher than ours, even though the richest 20% of Americans live longer on average than the richest 20% of Canadians.

Side note: lots of people take issue with life expectancy as a health metric, especially when comparing one country to another, and with some good reasons.  But the data we're discussing here is mostly exempt from those critiques, much more info and sources in the doobly-doo below.

Right, so this growing discrepancy in life expectancy is not normal and it is not natural.  We don't have to accept that life span will vary dramatically within a country based on where you live, but right now in the United States, that problem is getting worse, not better.   That seems to me deeply wrong.  I mean, our Declaration of Independence famously names three inalienable rights that Americans should enjoy, and before liberty and the pursuit of happiness, there is life.  Hank, I'll see you on Friday.

Actually, no, I will see you tomorrow for a surprise bonus Vlogbrothers video, and then I'll see you on Friday.