I was somewhat surprised by the following news report that about 10% of folks in the U.S. carry no cash on a daily basis. In fact, (according to them) 78% carry less than $50, and 49% less than $20, and fully 9% nothing. The link is:
http://www.cnbc.com/id/101664403

This is a lot less (given present prices) than I do. Without going into numbers, I carry enough for: 1 full tank of gas at 4-5 dollars a gallon; some food and water (e.g. 1 day's worth), and enough to cover miscellaneous out of pocket.

An example of how this helped me: about 3 years ago I got a flat tire and pulled off the road to change it. Due to some then unresolved medical problems, I could not quite change it by myself (but was working at it) when a homeless guy came by and offered to do for me for $20. He did, I had the cash and it was well spent. (BTW, it was a busy road and no one else stopped. . .)

What are your ideas on carry of cash on an EDC basis and how much or for what contingencies?