Money

Currency

The U.S. monetary system is very simple: The most common bills are the $1 (a "buck"), $5, $10, and $20 denominations. There are also $2 bills (seldom encountered), $50 bills, and $100 bills (the last two are usually not welcome as payment for small purchases). All the paper money was recently redesigned, making the faces on them disproportionately large, but the old-style bills are still legal tender.

Coins come in seven denominations: 1¢ (1 cent, or a penny); 5¢ (5 cents, or a nickel); 10¢ (10 cents, or a dime); 25¢ (25 cents, or a quarter); 50¢ (50 cents, or a half dollar); the gold-colored Sacagawea coin, worth $1; and the rare silver dollar.

Note: The "foreign-exchange bureaus" so common in Europe are rare even at airports in the U.S., and nonexistent outside major cities. It's best not to change foreign money (or traveler's checks denominated in a currency other than U.S. dollars) at a small-town bank, or even a branch in a big city; in fact, leave any currency other than U.S. dollars at home -- it may prove a greater nuisance to you than it's worth.

Traveler's Checks

Traveler's checks are widely accepted, but make sure that they're denominated in U.S. dollars; foreign-currency checks are often difficult to exchange. The three traveler's checks that are most widely recognized -- and least likely to be denied -- are Visa, American Express, and Thomas Cook. Be sure to record the numbers of the checks, and keep that information in a separate place in case they get lost or stolen.

Credit Cards & ATMs

Credit cards are the most widely used form of payment in the United States: Visa (Barclaycard in Britain), MasterCard (EuroCard in Europe, Access in Britain, Chargex in Canada), American Express, Diners Club, and Discover. There are, however, a handful of stores and restaurants in Montana and Wyoming that do not take credit cards, so be sure to ask in advance.

The easiest and best way to get cash away from home is from an ATM (automated teller machine). The Cirrus (tel. 800/424-7787; www.mastercard.com) and PLUS (tel. 800/843-7587; www.visa.com) networks span the globe; look at the back of your bank card to see which network you're on, then call or check online for ATM locations at your destination. Be sure you know your personal identification number (PIN) and daily withdrawal limit before you depart. Note: Remember that many banks impose a fee every time you use a card at another bank's ATM, and that fee can be higher for international transactions (up to $5 or more) than for domestic ones (where they're rarely more than $2). In addition, the bank from which you withdraw cash may charge its own fee. To compare banks' ATM fees within the U.S., use www.bankrate.com. For international withdrawal fees, ask your bank.