Exchange Students Academic Competition Opportunities

As the title suggests, are there any academic (particularly STEM) competitions that allow non-US citizens to participate?
I took the local section chemistry olympiad last year but knowing that I won’t be selected to participate in the next round is extremely disappointing. It is so frustrating that I have come to this supposedly “land of opportunities” away from my home while being unable to participate in these competitions simply due to my nationality and citizenship.

The particular competitions you are looking at are the US selection process for the international science olympiads. Students need to be a citizen or resident of the country they wish to represent in the international round. While you may not be eligible to represent the US, you would be eligible to represent your country of citizenship. Have you researched that country’s selection process for the international science olympiads?

There are other prestigious privately-sponsored competitions (mostly project-based) that are open to all high school students in the US, including:

[The Intel Science Talent Search](The Future of Education Technology and Solutions - Intel)
[The National Junior Science and Humanities Symposium](http://www.jshs.org/)
[The BioGENEius Challenge](http://www.biotechinstitute.org/go.cfm?do=Page.View&pid=89)
[The Google Science Fair](Google for Education - Online Resources for Teachers & Students)