Boston officials are considering ditching age-based year groups in the city's secondary schools, allowing pupils to study at their own pace instead.
High-fliers could complete their secondary education in three years while students needing longer could take up to five, under the radical plan. US high schools usually span four years to age 18.
The measure would "reduce student alienation and support students in progressing in a way which is more developmentally-appropriate", said Boston schools chief Thomas Payzant.
If adopted, which could be as early as next week or in September, it would mark the first time such a drastic re-engineering of the American grade system has been attempted on a large scale.
One of the pioneers of self-paced study is Alaska's isolated Chugach school district. There, the approach was a catalyst in turning around dismal student performance.
"It was really freeing for students to work at their own level," said Debbie Treece, Chugach's quality schools coordinator.
But rolling out the policy in Boston is a different proposition.
Mr Payzant said it would go "hand in hand" with plans to split the city's comprehensives into small and specialised schools admitting no more than 400 students next year, allowing more personalised instruction.
The move would also mean students failing courses would not have to repeat a whole year: a policy, common across America, which has seen three out of ten Boston high-schoolers fail to stay the course. Instead, students would only retake subjects they fail, otherwise advancing with their peers.
Under-performing elementary and middle-school students would still be held back, as this has proved effective, said Mr Payzant.
Boston joins a growing number of US cities, including Chicago and Houston, that have recently retreated from a blanket policy of holding back failing students.