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).
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.
Leave any currency other than U.S. dollars at home -- "foreign-exchange bureaus" common in Europe are rare even at airports in the United States, and it's best not to change foreign money at local banks.
Nationwide, the easiest and best way to get cash away from home is from an ATM (automated teller machine), sometimes referred to as a "cash machine" or "cashpoint." The Cirrus (tel. 800/424-7787; www.mastercard.com) and PLUS (tel. 800/843-7587; www.visa.com) networks span the country; you can find them even in remote regions. 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.
Credit Cards & Debit Cards
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. They also provide a convenient record of all your expenses, and they generally offer relatively good exchange rates. You can withdraw cash advances from your credit cards at banks or ATMs, provided you know your PIN.
Visitors from outside the U.S. should inquire whether their bank assesses a 1% to 3% fee on charges incurred abroad.
It's highly recommended that you travel with at least one major credit card. You must have one to rent a car, and hotels and airlines usually require a credit card imprint as a deposit against expenses. (Note: Businesses in some U.S. cities may require a minimum purchase, usually around $10, before letting you use a credit card.)
ATM cards with major credit card backing, known as "debit cards," are now a commonly acceptable form of payment in the same places that accept credit cards. In fact, many debit cards in the U.S. have a MasterCard or Visa logo. Debit cards draw money directly from your checking account. Some stores enable you to receive "cash back" on your debit card purchases as well. The same is true at most U.S. post offices.
Even with the advent of "instant money" from an ATM, many travelers still use traveler's checks, which are widely accepted in the U.S. Foreign visitors should make sure they're denominated in U.S. dollars; foreign-currency checks are often difficult to exchange.
You can buy traveler's checks at most banks. Most are offered in denominations of $20, $50, $100, $500, and sometimes $1,000. Generally, you'll pay a service charge ranging from 1% to 4%.
The most popular traveler's checks are offered by American Express (tel. 800/807-6233, or 800/221-7282 for cardholders -- this number accepts collect calls, offers service in several foreign languages, and exempts Amex gold and platinum cardholders from the 1% fee); Visa (tel. 800/732-1322) -- AAA members can obtain Visa checks for a $9.95 fee (for checks up to $1,500) at most AAA offices or by calling tel. 866/339-3378; and MasterCard (tel. 800/223-9920).
If you do choose to carry traveler's checks, keep a record of their serial numbers separate from your checks in the event that they are stolen or lost. You'll get a refund faster if you know the numbers.