Your driver's license is one of the most valuable things in your wallet. However, a foreign license doesn't have the same functionality as a US license. Let's take a look at how long you can drive with a foreign license in the US.
The short answer is, you can legally drive for up to six months in the US with a foreign license. In some states, this duration can be up to a year. In general, this is a very generous policy. It allows ample time for you to acquire a real license that can be used anytime, anywhere. The bottom line is, these policies really depend on the state.
In some states, a foreigner can drive nearly indefinitely as long as they continue to renew a temporary license. As long as they don't get into any trouble under the foreign license, they're good to go for a very long time. In other states, the policy isn't so lenient.
Foreigners need to limit their travel with a foreign license. If they want to accumulate a large number of miles, it needs to be done under a local license. You can check with the DMV for specifics on these policies. Info can also be found on the internet on the government's website.
The rule above doesn't always apply to tourists. If a person is in the country for vacation, they might only be legally allowed to drive for a much shorter time. In theory, they can drive for the duration of the vacation, and then they need to leave. There's no good reason for them to drive for an extended period of time.
If you declare a vacation to be your purpose of travel and are found to be in the US many months later driving around, you could face serious consequences. It really depends whether you have officially declared yourself as a tourist. These legal proceedings can often be complicated, so it's best to assume that you are a tourist if your status isn't explicit.
In addition, "tourist" isn't always a formal term. It can simply refer to your place of stay, whether it is with a friend or at a hotel or in an apartment. Keep in mind that the legal definition of tourism doesn't always coincide with the state's definition. We're afraid it's an incomplete answer; you really have to check with the state's DMV for specifics. In general, a person here for a vacation is treated as a tourist and is assumed to possess a foreign license.
Visas complicate all of the above. A work visa can exempt a person from any rules and allow their foreign license to be valid forever. Depending on the type of visa, all that might be necessary is a renewal each year. You can go to the DMV, explain your work situation, and receive a permit to drive as a foreigner.
Once again, it's crucial to check this on a state by state basis. States with high numbers of foreign workers are understanding of all of the above and have few issues with foreign licenses. Even if you get pulled over at a traffic light, it's not the end if you have a valid occupation.
On the other hand, some states are less tolerant of visas. They consider visas to fall under a temporary status, which must be addressed sooner or later. In essence, these states want you to obtain a formal license that will verify your reason for being in the US.
Fortunately, the rules for a green card are much more straightforward. Green card holders are more or less good to go indefinitely. Their foreign licenses will be treated as US licenses for all intents and purposes.
When it is called into question, all they have to do is present their green card to clear any issues. Because green card holders will be naturalized after an appropriate amount of time, the duration of their stay is pretty much irrelevant. They have a valid reason for driving in the US and won't be stripped of their license in the near future.
You can most definitely drive with a foreign license in the US, although for a limited duration. After the time limit is up, you'll either need to cease driving or acquire a US license. There are serious fines and punishments for anyone found to be driving with a foreign license after the period is done.