The problem arose, because in the presentation of the SSNs in the table, they are formatted like most Americans expect, 123-45-6789. However, when the tablesorter started doing the sorting, it actually performed the arithmetic on the field and sorted the result, rather than the string. I post this because, admittedly, it took me quite a while to figure out how the sort was behaving, and maybe this will save someone else some time.

So, I tried to add the custom parser. Following these the tablesorter docs and a blog post by Ori Peleg. I got this to work, sorta. I stripped out the dashes, making the SSNs just numbers and it would sort. But only one direction. Meaning they’d come in random and I could use the tablesorter to sort them descending, but clicking the header again would not sort ascending. Furthermore, it broke the rest of the sorters. I am sure this is all in the way I coded, but I never got it to work through jquery.

I ended up using PHP to replace the dashes with spaces and they sort fine using the default tablesorter sorting.