A process permitted in some states whereby voters may put proposed changes on the state constitution to a vote if sufficient signatures are obtained on petitions calling for such a referendum

The process allowing voters to propose changes to a state constitution if they can get sufficient signatures on the petitions, is called an "Initiative Petition"

Explanation:

In the United States, an "Initiative Petition" grants people the right to make changes to certain state laws if they can get a certain minimum number of signatures from registered voters, on a petition calling for such changes.

Washington DC along with twenty six other states in the United States, currently allow initiative petitioning.