cut ()

At Mon, 31 Dec 2012 22:25:25 +0000,

The issue is that, for Utah, I am getting an <NA> instead of (42,48.7] in the ob_mrj_cat column.

The problem is likely due to comparisons of floating point numbers.
Try moving your lower and upper bounds out a tiny bit.  When I add

  c(-1e-8, 0, 0, 0, 0, 1e8)

to the result of quantile, I don't get any NAs.

Neal