Donald Trump is pretty spry and energetic for an old guy - he's currently 71 years old, and seems to have more energy than I do (and I'm about 20 years his junior). But is he the oldest US president? Well, as with many questions ... it depends. Follow along as we analyze some data about all the past US presidents, and create graphs that answer this and many other questions!

Here's the graph that got me thinking about this topic. It was created and posted on the 'data is beautiful' reddit forum, by the user Brennejm.

It was an interesting graph, but there were several things I wanted to improve.

First, the age numbers along the axis were too small to read.

There were too many bold, attention-grabbing colors, so I didn't visually know what to pay attention to.

The color legend represented two distinct things ... but it was not obvious they were two distinct things.

The small colored bar segments along the left visually appear like they are part of the age bars, artificially increasing the perceived length of the bars.

There is no date stamp letting you know when the graph was generated (each day, the bar lengths of the living presidents get slightly more out-of-date).

There is a typo in at least one of the names (Jonh Adams).

And there is no title to tell you what the graph is all about.

I decided to use some data from Wikipedia, and create my own version of the graph. Here are some of the changes and customizations I made:

I made the ages text along the axis larger and easier to read.

I moved the presidents' names to the inside of the bars.

I used a lighter color for the main part of the bar, and a bright color for just the presidential term of office.

I used colored dots to show how the presidents died, rather than the small square bar segments.

I chose different colors for the dots (it didn't seem right to use orange for 'still alive').

I show separate color legends for the dot colors, and the bar segment colors.

I added an arrow to the end of the bars for the still-living presidents (showing that their age continues to increase).

I copy-n-pasted the data from the original source, reducing the chance of making typos myself.

I add a title describing the graph, and a footnote with a date stamp showing when it was created.

And, if you click the image below, you can see the interactive version with HTML mouse-over text showing the exact age data for each bar segment.

So, who's the oldest US president? If you mouse over the interactive graph, you can easily find that ...

Donald Trump was 70.6 when elected as president, making him the oldest elected to his first term as president.

when elected as president, making him the oldest to his first term as president. Ronald Reagan was 78.0 at the end of his last term, making him the oldest serving as president.

at the end of his last term, making him the oldest as president. And at 93.5, George H. W. Bush has reached the oldest age of anyone who has served as US president.

Tricks and technical details

This was some fun data to explore, and the new(ish) SAS yrdif() function certainly made it easy to calculate the ages. As with most of my graphs, I used a lot of data-driven annotate to customize things like: adding the colored dots to the left, moving the president names from the regular position to inside the bars, and adding the age axis to the top of the graph. And I used Proc Gplot's note statement to create the custom legend at the bottom of the graph.