The Twelfth Amendment (Amendment XII) to the United States Constitution provides the procedure for electing the president and vice president. It replaced the procedure in Article II, Section 1, Clause 3, under which the Electoral College originally functioned. The amendment was proposed by Congress on December 9, 1803, and was ratified by the requisite three-fourths of state legislatures on June 15, 1804. The new rules took effect for the 1804 presidential election and have governed all subsequent presidential elections.
Under the original Constitution, each member of the Electoral College cast two electoral votes, with no distinction between electoral votes for president or for vice president. The presidential candidate receiving the greatest number of votes—provided that number was at least a majority of the electors—was elected president, while the presidential candidate receiving the second-most votes was elected vice president. In cases where no individual won the votes of a majority of the electors, as well as in cases where multiple persons won the votes of a majority but tied for the most votes, the House of Representatives would hold a contingent election to select the president. In cases where multiple candidates tied for the second-most votes, the Senate would hold a contingent election to select the vice president. The first four presidential elections were conducted under these rules.
The 12th amendment did not impose any specific requirements on how states should allocate electoral votes. Electoral votes are entirely different than normal votes. The 12th amendment is referring to electoral votes not normal votes that you and I cast. States aren’t even required by the constitution to have an election. They aren’t required to hold a popular vote or election to determine how their electoral votes are awarded in presidential elections either. Instead, it is up to each state to determine its own method of selecting electors who will cast the electoral votes on behalf of the state.
https://en.wikipedia.org/wiki/Twelfth_Amendment_to_the_United_States_Constitution
It’s not a states thing.
The 12th amendment did not impose any specific requirements on how states should allocate electoral votes. Electoral votes are entirely different than normal votes. The 12th amendment is referring to electoral votes not normal votes that you and I cast. States aren’t even required by the constitution to have an election. They aren’t required to hold a popular vote or election to determine how their electoral votes are awarded in presidential elections either. Instead, it is up to each state to determine its own method of selecting electors who will cast the electoral votes on behalf of the state.