How many times can a US citizen get the 30-day visa exemption and do they need to leave Thailand?

A US citizen can initially enter Thailand with a 30-day visa exemption. After utilizing this exemption, they can apply for a single 30-day extension by paying the 1,900 Baht fee at the immigration office. However, after this extension, they must leave the country to obtain another 30-day visa exemption. It is important to note that a border run can be performed to get a new stamp, but this can only be done twice a calendar year.