Dr. Marcus J. Newsome is retiring as superintendent of Petersburg Public Schools at the end June with his school improvement plan only half completed.

The 65-year-old educator who has spent three years in the post made the announcement Wednesday afternoon. He plans to wrap up a 40-year career in education that includes 16 years as a superintendent.

Dr. Newsome has led Petersburg schools since July 2016, when he delayed his retirement to accept the post following a successful tenure as superintendent in Chesterfield County.

At the time, Gov. Terry McAuliffe and the state secretary of education, Anne Holton, encouraged Dr. Newsome to take on Petersburg, one of the most troubled school districts in Virginia that regularly ranked around the bottom in student achievement.

In his letter Wednesday to the Petersburg School Board, Dr. Newsome wrote, “I share your pride in knowing that we are in a much better place than we were three years ago. ... Together, we have established a solid foundation for the future.”

While state data has yet to show much improvement in pass rates on reading, writing and math tests, Dr. Newsome cited an array of changes, including providing laptop computers loaded with textbooks to every student in grades two through 12 and introducing all students to computer coding.

During his tenure, he said there has been a 20 percent increase in students reading on grade level. He also pointed to improved budgeting, a free teacher supply store and improved training for assistant principals.

He also led the creation of a five-year strategic plan launched last year aimed at upgrading the student learning experience and that was the basis of the corrective action plan the school system signed with the state Department of Education last October.

He also touted the stronger relationships that have been created with the city government, as well as with faith, business and nonprofit groups to build support for the school district.

Petersburg has eight schools and serves about 4,000 students.

School Board Chairman Kenneth L. Pritchett praised Dr. Newsome for his work and expressed regret that he is leaving.

“The School Board and I wish that Dr. Newsome’s retirement announcement could be delayed for several more years. We know that our schools are stronger than they were three years ago.”

He said the seven-member board would quickly begin the process of finding a “talented and experienced superintendent to built on the foundation that we and Dr. Newsome have laid.”

Mr. Pritchett stated that the board has hired B.W.P. & Associates, an educational leadership search firm, to take charge of recruiting applicants.

Dr. Newsome began his career as an art teacher in public schools in Washington and later switched to mathematics in joining the Prince George’s County school system in Maryland, where he rose through the administrative ranks to executive director.

Newport News tapped him in 2003 to lead its school division, and Dr. Newsome was lauded for the academic improvements that won recognition for that city’s high schools.

In 2006, he became superintendent of Chesterfield County Public Schools, which saw improvements in the percentage of students passing state SOL tests and graduation rates reach all-time highs. He also switched students from textbooks to laptop computers and won recognition from the Obama administration in 2015 for changing to the digital environment.