After an 84-year-old driver plowed through an elementary school lunchroom this week, killing an 8-year-old boy, his mother pressed lawmakers to bar the elderly from getting behind the wheel.

"We very much support a mandatory limit on the driving age for seniors," Amanda Wesling wrote in a missive directed at driver Grace Keim, who authorities say was en route to a driving class at a senior citizen's center Monday when she struck Ryan Wesling.

Wesling's plea raises new questions about how old is too old to drive, an issue state legislatures continue to grapple with in the wake of similar tragedies in recent years. While many states have enacted or are considering tougher testing for older drivers, they're weighing those changes against the rights of millions of older people to have the independence a license allows.

Among the incidents prompting calls for change:

— In November, an 89-year-old man whose car hurtled through a farmers market in California in 2003, killing 10 people and injuring more than 70 others, received five years of probation because a judge deemed him too ill to go to prison.

— Last August, a sport utility vehicle driven by an 89-year-old man plowed into pedestrians and vendors at an open-air public market in Rochester, N.Y., injuring 10 people.

— In October 2005 in North Dakota, an 87-year-old woman on her way to a doctor appointment smashed her car into the hospital's lobby, injuring five women.

At least two dozen states and the District of Columbia have laws singling out older drivers for special attention, from required road tests to vision examinations, according to the Insurance Institute for Highway Safety.

In Connecticut, there's a legislative push to require automatic retesting of anyone over 75 who has had more than two wrecks in a calendar year, according to the National Conference of State Legislatures. In New York, a pending measure would halve to two years the renewal period for anyone over 70.

"Different states are doing different things, but they're addressing the issue," said Anne Teigen, a research analyst for the NCSL. Still, she says, legislatures are trying to balance safety concerns against the unwavering fact that older Americans want to drive.

Illinois has some of the nation's toughest restrictions on older drivers, joining New Hampshire in requiring a road test for renewals after age 75. Illinois also is among at least 15 states that have an accelerated renewal schedule for older drivers, requiring renewals every two years from ages 81 to 86, and then every year after that.

Democratic Illinois state Rep. Kurt Granberg says setting an age for drivers to hand over their keys wouldn't be appropriate because "everyone's different." But he says he wouldn't be surprised if Ryan's death prods lawmakers to revisit the state's requirements for older drivers.

Advocacy groups for the elderly urge states not to overreact to each incident, noting that accidents happen in every age group and that taking away an older person's license could rob them of their independence.

"The issue is not age; it has to do with the person's physical and mental limitations, and that goes beyond age," said Beverly Moore of Illinois' AARP.

Older drivers, she says, still tend to be more cautious behind the wheel, and family members can be involved in helping decide when a driver should give up the keys.

Studies have shown that vision, reaction time and other driving skills can diminish as drivers age.

Statistics from the Insurance Institute show that older drivers generally are as safe as other age groups until they reach 75, when they tend to have more accidents. Drivers 85 and older are about as likely to be involved in a fatal crash as those ages 16 to 19, but they're more likely to die than others in car crashes because their bodies are frailer, according to the institute.

Keim's license was up for renewal March 3, her 85th birthday, and her driving record shows no citations, according to state records. Investigators have not said what caused her to drive up a dead-end drive and never stop, hurtling through Shiloh Elementary's cafeteria, killing Ryan and injuring two schoolmates.

While sympathetic to Ryan's family, 67-year-old Joan Juergens considers his death "totally a freak occurrence" that shouldn't require stiffening Illinois' licensing requirements for older drivers.

"I don't think you can broadbrush one age group and say it can't drive anymore. It's unfair," Juergens said.

Others aren't so sure. At 66, Mary Baum says she wouldn't mind state lawmakers taking a fresh look at Illinois' licensing protocol after an elderly aunt of her husband's flunked a drivers license test, then admitted to the family that her vision was failing from age-related macular degeneration.

"Something has to be done," Baum said. "Some are qualified to drive, some are not. And I would not want to be on the road if I'm not."