Get it before
you travel
while it's a very bad idea to arrive in the US without any cash at
all in your pocket, you probably don't want to carry too much. You're
not not likely to have it stolen (unless you flash it around), but
it's quite possible that you'll lose it. My own personal routine is
to start off with about $100 in cash.
Cash can be had
from numerous different places - your own bank, online, travel agent
or at the airport. Some banks offer "commission free" currency,
and you may be able to order it for delivery (but there'll be a charge
for the delivery). But watch the exchange rate, as you may find that
those offering low or no commission are working at poorer exchange
rates.
Cash a traveller's
cheque
You can either rely on the change when you pay for something with
a traveller's cheque, or you can cash one at a bank or "check-cashing"
facility.
Use an ATM
There are cash machines all over the US. You'll find them in malls,
gas stations, supermarkets and, of course, banks. Whether or not you
can use them, and whether you'll be charged a fee, will depend on
the type of card that you have.
Most US ATMs
operate on either the Mastercard (Cirrus/Maestro) or Visa (Plus) networks
and if you need to find out which machines are available in the area
you're staying, the relevant Web sites (Mastercard or Visa) can help.
You may also be able to use your credit card, although you'll almost
certainly have to pay an additional "cash transaction" charge.
Some ATMs will
charge a fee, but you'll be advised of this in advance, and you may
also have to pay a fee through your bank. In general, the overall
fee is likely to be fairly small (perhaps $1.50 at the ATM and/or
1.75% by your bank). You may only want to use an ATM if you're desperate
for cash, but I do know some people that rely on ATMs exclusively
for all their cash needs.