The election is three weeks off, the size of any anti-Trump congressional wave is not precise enough to calibrate, but the look of the next year’s Senate is nonetheless starting to come into view.

Regarded from a high altitude, the north side of the Capitol will retain the same appearance it’s had throughout history. No matter what happens Nov. 8, there’s no getting around a continued oversample of white male senators in middle age or older, meaning the chamber of 2017 will once again look less like America than like the lobby of a venerable law firm from the “Mad Men” era.

But at ground level, the membership is also poised to undergo a few subtle but important shifts away from its hegemonic past. There may not be any true demographic history-makers in the Senate’s potential Class of 2016, but collectively they are a decidedly younger and slightly more ethnically varied bunch than the members they would be joining.

They are also a more youthful, racially mixed, better educated and closer to gender-balanced group than the incumbents they might be replacing — a sort-of senatorial “wins above replacement player” statistic, to adapt an in-vogue baseball metric.

Barring a late and cataclysmic eruption of the political landscape, no more than 14 states will elect new senators next month — and only 18 challengers or open-seat candidates in those places have a viable shot at winning. These are the potential freshmen. In the main, the measure of additional diversity shaping the Senate will be closely correlated to the size of the down-ballot Democratic surge.