The rules are different on the federal, state, and local level as it pertains to the rights of immigrants to vote. While all natural U.S. citizens have been granted the right to vote, the rules are different for naturalized U.S. citizens and permanent residents.
Naturalized U.S. citizens are people who were formerly citizens of a foreign country before being granted U.S. citizenship. Immigrants who have U.S. citizenship have the same voting privileges as natural-born citizens.
Permanent residents are those who have the ability to work in the U.S. but do not have U.S. citizenship. They are colloquially known as Green Card holders. While Green Card holders are not eligible to vote in Federal elections, some states and localities do allow Green Card holders to vote. Although undocumented immigrants are not eligible to vote in the United States, the City of Boulder does allow undocumented immigrants to serve on city boards and commissions.
No matter your immigration status, you should engage in civic activity. If you are currently not eligible to vote, engage civically by donating, volunteering, and sharing information about candidates who care about the same issues as you.