The only legal digital currency in the United States is the US dollar. While there are many different cryptocurrencies available for trade and investment, the US government only recognizes the US dollar as legal tender for all transactions within the country.

The US dollar is issued and regulated by the United States Treasury Department and the Federal Reserve System. It is the official currency of the United States and is widely accepted for all types of transactions, from buying goods and services to paying taxes and debts.

While cryptocurrencies like Bitcoin, Ethereum, and others have gained popularity in recent years, they are not considered legal tender in the United States. This means that while you can buy, sell, and trade these digital currencies, they are not officially recognized by the government as a form of legal payment.

It is important to note that the legality and regulation of cryptocurrencies can vary from country to country, and it is always important to do your research and understand the laws and regulations in your own country before investing in or using digital currencies.