IB and Common App provide guides about how to apply to US Universities

US Universities are autonomous and students must apply to each institution directly. The Common Application allows students to apply to many of them through a single application process. However, some of them do not use it and have their own application process.

After choosing the university you're going to apply to, check their application process and requirements. Even universities using the common application may have their own specific requirements, which may include extra questions, essays, and even portfolios. Therefore, be prepared to write more than one essay!

Admission officers look at student performance holistically, taking into consideration their SAT or ACT scores, biographical information, education background, letters of recommendation, personal essays, etc. Nearly all institutions consider the IB Diploma performance as well.

Having all that in mind, it's very important to start early. Filling out the application takes time, as you'll need to gather a lot of information. Many colleges will also ask for recommendation letters, so choose recommenders ahead of time to give them enough time to write them. Stay organized and do not lose the deadlines!

Read more on the sources below:

Guide for IB students applying to US institutions https://www.ibo.org/contentassets/5895a05412144fe890312bad52b17044/recognition---international-student-guide-us--march2016---eng.pdf.pdf

Application guide for first-time students

https://www.commonapp.org/apply/first-time-students