Idaho is pretty sparsely populated and mainly rural which leads to lower car insurance rates. According to World Atlas, Idaho has the seventh least population density in the country. There are roughly 20 people for every square mile. Wide-open spaces with few people mean fewer cars out on the road and fewer accidents, everything an insurance company loves.
A lot goes into an auto insurance rate quote, including your ZIP code, coverage levels, marital status, annual mileage, driving history and vehicle make, year and model. In most states, your gender and credit history are also used to determine rates. And again, the reason auto insurance comparison shopping is so important is because rates between companies are different for each person, too.