Apparently Vermont technically still has electrocution on the books for treason.

All 26 states with the death penalty for murder provide lethal injection as the primary method of execution. As of 2021, South Carolina is the only autonomous region in the United States of America to authorize its 1912 Electric Chair as the primary method of execution, citing inability to procure the drugs necessary for lethal injection. Vermont's remaining death penalty statute for treason provides electrocution as the method of execution.

However, given that very few people in the US have ever been convicted of treason at all -- despite people liking to claim that something is "treason", it's actually an extremely narrowly-defined crime -- much less under Vermont state law, that's probably largely academic.

https://en.wikipedia.org/wiki/Treason_laws_in_the_United_States

Treason is defined on the federal level in Article III, Section 3 of the United States Constitution as "only in levying War against [the United States], or in adhering to their Enemies, giving them Aid and Comfort." Most state constitutions include similar definitions of treason, specifically limited to levying war against the state, "adhering to the enemies" of the state, or aiding the enemies of the state, and requiring two witnesses or a confession in open court. Fewer than 30 people have ever been charged with treason under these laws.

Death sentences for treason under the Constitution have been carried out in only two instances: the executions of Taos Revolt insurgents in 1847, and that of William Bruce Mumford during the Civil War. 

Constitutionally, U.S. citizens who live in a state owe allegiance to at least two government entities: the United States of America and their state of legal residence. They can therefore potentially commit treason against either, or against both. At least 14 people have been charged with treason against various states; at least six were convicted, five of whom were executed. Only two prosecutions for treason against a state were ever carried out in the U.S.: one against Thomas Dorr and the other after John Brown's conspiracy. It has often been discussed, both legally and in matter of policy, if states should punish treason.

Neither of those was in Vermont -- one was in Rhode Island and the other Virginia, and the only instance of the two in which a death sentence was applied was in Virginia, after the John Brown uprising.