WASHINGTON – Jerry Wiseman notices it’s harder to turn and check his car’s blind spots at age 69 than it was at 50. So the Illinois man and his wife took a refresher driving course, hunting tips to stay safe behind the wheel for many more years – a good idea considering their state has arguably the nation’s toughest older-driver laws.

More older drivers are on the road than ever before, and an Associated Press review found they face a hodgepodge of state licensing rules that reflect scientific uncertainty and public angst over a growing question: How can we tell if it’s time to give up the keys?

Thirty states plus the District of Columbia have some sort of older-age requirement for driver’s licenses, ranging from more vision testing to making seniors renew their licenses more frequently than younger people. At what age? That’s literally all over the map. Maryland starts eye exams at 40. Shorter license renewals kick in anywhere from age 59 in Georgia to 85 in Texas.