Some states have boards to lead elections, others rely on a secretary of state, but not one of the 50 U.S. states has election leadership intentionally designed to be impartial. In this respect, the U.S. is a major outlier internationally.
In practice, most American elections are run impartially, but there are few ways to ensure they will be. A study conducted by the law firm Ropes & Gray concluded that no U.S. state has conflict of interest laws constraining election chiefs from conflicted behavior.
Instead, U.S. elections must rely on the ethics of officials, many of whom come to their position as members of a political party elected by that party’s supporters. This system has failed in the past, and with increasing polarization it could very well fail again.