Each state has different requirements when it comes to auto insurance. In some places, you can't register a car without showing proof of liability insurance. Other states use a kind of honor system that doesn't require proof from drivers until they have accidents or tickets on their records.
Nonetheless, states do mandate that a minimum of liability coverage be sold. In other words, you can't walk into your insurance agent's office and buy only $2,000 worth of coverage. If you're going to buy it, you have to buy it for at least the amounts listed in the table.
What's the key to buying auto insurance? You need enough to protect yourself and your family in the case of an accident, regardless of whether it's your fault or the other driver's.