JSFiddle - React, Tailwind, and code Playground

HTML

<form name="selEstadoRepresentante" id="form" method="post" action="/representantes/?uf=">
  <select class="selectpicker" name="state" id="state">
    <option value="">Selecione</option>
    <option value="AC">Acre</option>
    <option value="AL">Alagoas</option>
    <option value="AP">Amapá</option>
    <option value="AM">Amazonas</option> 
    <option value="BA">Bahia</option>
    <option value="CE">Ceará</option>
    <option value="DF">Distrito Federal</option>
    <option value="ES">Espírito Santo</option>
    <option value="GO">Goiás</option>
    <option value="MA">Maranhão</option>
    <option value="MT">Mato Grosso</option>
    <option value="MS">Mato Grosso do Sul</option>
    <option value="MG">Minas Gerais</option>
    <option value="PA">Pará</option>
    <option value="PB">Paraíba</option>
    <option value="PR">Paraná</option>
    <option value="PE">Pernambuco</option>
    <option value="PI">Piauí</option>
    <option value="RJ">Rio de Janeiro</option>
    <option value="RN">Rio Grande do Norte</option>
    <option value="RS">Rio Grande do Sul</option>
    <option value="RO">Rondônia</option>
    <option value="RR">Roraima</option>
    <option value="SC">Santa Catarina</option>
    <option value="SP">São Paulo</option>
    <option value="SE">Sergipe</option>
    <option value="TO">Tocantins</option>
  </select>
  <input class="btBuscar" name="btBuscar" value="BUSCAR" type="submit" title="Buscar">
</form>

JavaScript

$(function()
{
  $('.selectpicker').on('change', function()
  {
    if($(this).val() && $(this).val() == 'AM')
    {
        $('#form').submit();
    }
  });
});