He held positions in the U.S. Forest Service, the Tennessee Valley Authority, and the U.S. Department of Labor; he was also a member of the Technical Alliance where he participated in the Energy Survey of North America.

[1] MacKaye helped pioneer the idea of land preservation for recreation and conservation purposes and was a strong advocate of balancing human needs and those of nature; he coined the term "geotechnics" to describe this philosophy.

Shortly after William died of a sudden respiratory disease in 1889, the family moved to Washington, D.C. An indifferent student, MacKaye once described school as "a place that boys like to run away from".

[6] Drawn to the study of the natural world, he often pursued knowledge on his own; he spent much time in the Smithsonian, making sketches of the abundant collections and volunteering to help scientists in their labs.

[7] He befriended assistant curator James Benedict and attended lectures given by Civil War hero John Wesley Powell and arctic explorer Robert Peary.

[8] His early immersion in nature helped him cope with tragedy that eventually struck the MacKaye family; his frequently absent father died in 1894, when Benton was fourteen.

[9] While attending high school in Cambridge, he began charting the landscape around Shirley Center, documenting vegetation, landforms, rivers, and roads in numbered notebooks.

"[7] After dropping out of school in order to prepare for college entrance exams on his own, in 1896 MacKaye followed his brothers—James, an engineer and philosopher, and Percy, a dramatist and poet—to Harvard University, where he studied geology.