The U.S. dollar is the currency in the Commonwealth. Stateside-style banks include the Bank of Guam, Bank of Hawaii, Bank of Saipan and Union Bank. On your arrival in the CNMI, it is easier and more convenient to bring credit cards or traveller's cheques in US funds for immediate use.
Cash is best .
A purchase receipt may be needed to cash traveller's cheques. To open a bank account you will need a U.S. Social Security number. Saipan offers the same postal rates and services as any post office in the United States. Most people here have private post office boxes, however, home delivery can be arranged. Most mail from the states takes about a week to arrive and boxes tend to take up to 3 months to arrive.