The Washington Examiner’s Byron York raised an interesting point about President Trump on Friday.

“It’s remarkable,” York wrote, “that after all that has happened, Trump’s favorable and unfavorable rating — not his job approval, but whether people hold a favorable or unfavorable view of him — is virtually the same as it was on election day.”

He points to the RealClearPolitics average of polls to make his point. On Nov. 8, 37.5 percent of Americans viewed Trump favorably and 58.5 percent viewed him unfavorably. In the most recent average, similar numbers: 39.6 percent view him favorably and 55.2 percent unfavorably. How is it that Trump’s approval rating could have slipped but his favorability ratings stayed the same?

There’s an easy answer to that: They haven’t.

Over the course of his time in politics, Trump’s favorability rating has seen a lot of movement. That doesn’t hold true in every respect, mind you. Consider the views of Democrats, who’ve been asked how they feel about Trump by Quinnipiac University since May of 2015. Democrats have consistently held pretty negative opinions of Trump.

But among Republicans there’s been huge movement. When he first flirted with running Republicans held strongly negative views of him. But over time, those views shifted strongly — surprisingly strongly — in his favor. Note that the scale of the graph below covers 80 percentage points, versus the 30-point spread on the chart above.

The net result? Trump’s favorability ratings among all poll respondents climbed once Trump became a serious candidate in late 2015, and increased dramatically once he won the presidency.

The line on that graph, though, shows the broad trend of Quinnipiac’s poll results — including a downward dip in recent surveys.

We can look at this another way. Here’s the net favorability of Trump by party over time; that is, the percentage of those who view Trump favorably minus the percentage who view him unfavorably.

Notice how the increase in net favorability among Republicans increases after the primaries and after the general — and how among members of every partisan group, he was viewed more favorably right after the election but then saw his numbers fall. (Notice too that independents are net negative and Democrats are much more strongly net negative than the Republicans are net positive, which is why Trump’s so far underwater.)

What York is doing is the equivalent of starting at sea level, driving over a mountain and, back at sea level, noting that your altitude is the same at the end as at the beginning. That mountain, though, is important.

Trump’s approval rating is calculated beginning at Jan. 20 (since it’s job approval, and that’s when he got the job). But York calculates his approval from November until now. One went over the mountain and came back to the same place. The other started at the top of the mountain and drove down. But the pattern has been the same.

To put a fine point on it, here’s the full RealClearPolitics net favorability and net approval over time.

Trump’s favorability has not stayed the same.