Great question. Picking a major is hard- I personally chose my major before I started college. But others will start taking general education credits first and take some classes to figure out their interests.
To see what popular majors in the US are, you could take a look at articles like the one below:
However, for choosing a major, instead of looking at what is popular, I would look at job outlook. You also need to consider what your interests are. For figuring out job trends and job outlook for different careers in the US, I would recommend looking at the Bureau of Labor Statistic's website. https://www.bls.gov
On the BLS website, you can search for any job (such as computer scientist or journalist) and look at the job outlook tab. This can help you figure out which careers will have a strong job outlook in the future.
Best of luck to you.