According to the Real ID Act of 2005, eight US states provide residents with IDs that don't meet the minimum security standards set by the federal government. What that means in practical terms is that folks planning on traveling domestically with a state-issued ID from the below states will eventually have to take a passport along with them.
The affected areas are:
Kentucky
Maine
Missouri
Montana
Oklahoma
Pennsylvania
South Carolina
Washington
Some more details: The above-mentioned states, which are just some of the ones currently under review, have until January 22, 2018 to comply with the Real ID Act. Check out this official map for an area-by-are breakdown.
According to Forbes, "some states have started working on offering federally approved issued IDs that would not require a passport for domestic air travel." But, given the usual red tape involved in these sorts of things, our advice is to go get yourself a passport no matter where you are from and then book yourself a vacation. Here are the best domestic day trips you can take, in case you need some inspiration.