Probably a naive question. With "Miller cylindrical" projection or many other "flat looking" projections, a small portion of Russia is showing on the upper left corner. What causes this? Is there any way to shift/pan the map to the left so that it is not breaking up like this? For example: https://observablehq.com/@chrispahm/building-the-world-life-expectancy-1960-2016-map-using-the-v

For most projections, the default aspect is to rotate [0, 0]. The tip of Russia being to the east of the antimeridian (180°), it appears "cut" to the left of the map. Usually you would rotate the projection by 10 degrees of longitude to get a proper separation in the Bering Strait rather than on the 180° line. You might also use a more precise rotation (11.6°, I believe), but that will make a standard graticule look awkward.

Thanks! Specifically, how do I "rotate" it? Is there a D3 method for that? Or should I do it in a tool like QGIS?

https://github.com/d3/d3-geo/blob/main/README.md#projection_rotate https://observablehq.com/@d3/three-axis-rotation