Why America is no longer a Constitutional Republic

The first presidential election in the United States where the popular vote determined the allocation of electoral votes was the election of 1824.
However, it wasn't until the 20th century that most states adopted the popular vote as the primary method for allocating their electoral votes.

April 8, 1913, 17th amendment – Senators elected by popular vote and no longer by state legislature

We are no longer ruled by law but by popular opinion

John Adams - “Liberty, once lost, is lost forever.”