Can you drive legally in Nepal with US drivers license?

nop...u need a DL from Nepal to legally drive here

If it's for short vacation, get the nternational drivers permit from AAA or NAC. With that permit and DL from US, u can drive legally in Nepal for 15 days. Thereafter u need DL from Nepal.

It takes more time than your vaccation time. I always used my US license for bike, could not dare to drive cars.

First hand experience,
Technically, you need international license or Nepali license to drive motor vehicles in Nepal. But if you have license of USA, which you can argue with traffic police that its international and you are allowed. Traffic police in Pokhara are different, they have seen a lot of tourists and they know what international license looks like. Anyway, though its not legally allowed, because of " almost illiterate " group of police in Nepal, you can get away with any state's license.
And a plus point if you wear glasses. Of you do wear glasses, then there is a restriction "B" on your license, which means, you cant drive without your prescribed glasses/contacts. But this serves as Class B category in Nepali license. (which refers to motor bikes).
So, if you are a " म देशको नियम मिच्दीन" type of guy, go get your international license. If not, you shall be fine depending upon how educated the police is who stops you.