And his "net" approval (subtracting disapproval) has been the worst among those 13 presidents every day of his presidency, and it's never been particularly close. Currently he's within a single percentage point of same-day Gerald Ford in approval, but at -18.3, his net approval is 9 percentage points worse than Ford's, and every other president was in positive territory at this point.
All of that with the more-or-less peace and something very close to prosperity -- the two things that generally drive whether U.S. citizens like their presidents or not.
While we can argue about whether he's flattened out in the mid-to-high 30s or if his popularity continued to gradually erode over the last several months, what is clear is just what an astonishing, and still not properly appreciated, achievement this is. Put aside questions about how well a start this bad predicts how he'll be seen in November 2018 or November 2020: To get this unpopular, this fast, and to do it in an era of relatively good times, is just breathtaking.
Granted, it's not quite true that because the president is so unpopular, everything he's done must feed into that unpopularity. But I do think it's impressive enough that our default should be that whatever he's doing is unlikely to be working on this score. I've seen people claim he's winning his fight against the NFL, for example, but the numbers certainly don't suggest that's the case.
In fact, Harry Enten at FiveThirtyEight estimates that Trump's net approval is a whopping 30 percentage points below where the economy suggests it should be.
That can't just be the tweeting, or the failure of the health-care bill, or any other single factor. It suggests that almost everything Trump is doing drives away potential supporters. If someone suspects they've found the exception, the burden is on them to prove it. #impeachtrump