Nearly 7.7 million American workers younger than 30 are now unemployed and three million dropped out of the labor force in the past month. Combined that’s nearly one in three young workers, by far the highest rate since the country started tracking unemployment by age in 1948.

Nearly 40 percent worked in the devastated retail and food service sectors. And as the most recently hired, young workers are typically the first let go and often the last rehired, especially those of color.

As our country’s leaders consider a range of solutions to address this crisis, there’s one fix that will put millions of young Americans directly to work: a 21st-century version of the Civilian Conservation Corps.

In 1933, when President Franklin Roosevelt created the C.C.C., he was facing, as we are today, the possibility of a lost generation of young people. The conservation-minded president’s idea was to hire young unemployed men for projects in forestry, soil conservation and recreation. By 1942, the 3.4 million participants in “Roosevelt’s Tree Army” had planted more than three billion trees, built hundreds of parks and wildlife refuges and completed thousands of miles of trails and roads.