The closest airport to Johnson City is Tri-Cities (an approximately 35-minute drive), which also has rental cars.
Tri-Cities Airport
There are additional rental car companies in Johnson City.
Johnson City has taxi services.
The area bus service, Johnson City Transit or JCT, is free for ETSU students. Always have a means of identification before taking the bus.
Johnson City Transit
Driving:
1) International individuals who will be in Tennessee for more than 30 days are considered Tennessee residents for driving purposes and must apply for a Tennessee driver's license within 30 days of arrival in the state.
Tennessee Driver Services
2) Vehicle insurance is mandatory in 48 of the 50 United States (including Tennessee). It is illegal to drive without car insurance. A simple internet search will list many companies which sell insurance.