Cash.

Cash. If you've ever traveled in an underdeveloped country, you know the drill. Lots and lots of cash. Because there are usually no credit card facilities, ATMs are rare, and changing money is a real pain-in-the-ass, and because you've got to constantly buy food, water, taxi fares, hotel rooms, travelers end up carrying around lots of cash.

We entered Uganda today and the visa at the airport was $50 per person. In US Dollars. So I peeled a hundred-dollar bill off my wad (we are crossing into Rwanda next week, and then back into Uganda, so that will probably be another $200 in visas) and handed it over to the border agent. He cheerfully tossed it into a drawer full of other travellers' precious large-denomination dollars and handed me a receipt. And some fancy passport stamps which allowed us into the country.

So at any given time we are carrying several hundred-dollar bills, a few hundred-thousand of the local currency (currently Ugandan shillings) and a few hundred of the regional currency (currently South African rand). And maybe a handful of Euros just for good measure (though we're keeping a wary eye on the Greeks to see if our Euros hold their value).

For the traveller, cash-based economies are problematic. What to do with all that cash? What if someone steals your bag and it has cash in it? What if you get mugged and someone takes your wallet? How much are you willing to lose in a given theft-event? Does it even matter, since a potential thief probably knows that you've got cash hidden in your socks and in secret pockets sewn into your pants as well as in the usual places like a wallet or back pocket? It's a real challenge.

But it's infinitely harder to deal with if you LIVE in a cash-only economy. If we get mugged we basically need to figure out a way to call home and have someone wire us more cash. Or get a credit card company to give us an advance against a new number. If you live in a cash economy then your life savings are hidden in empty tomato tins and buried in old beer bottles. And if you get robbed it's not just an annoyance but an existential crisis.

So the market has responded. We bought a very cheap cellphone and plugged in a local SIM card. (Becca can send along our Ugandan phone number if anyone wants to call!!). And, sure enough, one of the options on the phone is "Banking," which basically turns your cellphone number into a bank account and allows you to transmit payments, store savings, and withdraw cash as necessary. We've only been in Uganda a couple of hours so I have yet to see the system in action, but the idea of it is pretty compelling.