The best way I have found to handle this is to perform the rotation of the x-axis tick labels yourself. Why? Because NVD3 is not handling the rotation and associated translations properly. Look at your image, and you'll see that the library allows the rotation to translate the labels out from directly under the columns they represent. It also begins to mishandle the axis.tickPadding()
values, and so on.
The first thing that you need to do is to ensure that the chart has enough space for the translated labels, like so:
chart.margin({bottom: 60});
We can then translate and rotate the labels:
var xTicks = d3.select('.nv-x.nv-axis > g').selectAll('g');
xTicks
.selectAll('text')
.attr('transform', function(d,i,j) { return 'translate (-10, 25) rotate(-90 0,0)' }) ;
The labels now look like this: