us_regions = {
const west = ['02', '15', '06', '41', '53', '04', '08', '16', '35', '30', '49', '32', '56'];
const south = ['10', '11', '24', '54', '51', '40', '37', '48', '05', '21', '47', '40', '45', '01', '28', '13', '22', '12'];
const midwest = ['18', '17', '26', '39', '55', '19', '20', '27', '29', '31', '38', '46'];
const northeast = ['09', '23', '25', '33', '44', '50', '34', '36', '42'];
const custom = ['10', '24', '54', '40', '37', '40', '45', '13', '22', '12'];
const all = d3.merge([west, south, midwest, northeast]);
const continental = all.filter(d => d != '02' && d != '15');
return {west, south, midwest, northeast, all, continental, custom};
}