Clifton, who is in her 36th year as an educator and her 13th year leading TMS, will become the director of an education outreach arm of the American Association of State Highway and Transportation Officials.
Tupelo Superintendent Randy Shaver said the district hopes to have a successor named by Christmas break.
"I'm not so sure that we don't have the best candidate here in Tupelo, but we'll also be looking outside because that is in the best interest of our students," Shaver said.
Clifton will be the director of TRAC, the AASHTO's educational outreach for middle and high school students. TRAC stands for the Transportation and Civil Engineering Program.
Tupelo Middle School has been heavily involved with the TRAC program, which is the basis for the school's nationally recognized bridge building program and a part of its Information and Communication Technology-2 program.
"Leaving Tupelo Middle School is truly bittersweet," said Clifton, who has also worked in the Booneville and Union County school districts. "The students, teachers and parents have been like a family to me for 12 years and they will always have a special place in my heart.
"It is just time to retire, and I am looking forward to working with TMS in my role as director of the TRAC program."
Clifton said she will leave at the end of the current semester because she's needed in the new job then.
"I could not say enough good things about Ms. Clifton," Shaver said. "I wish she could wait until the end of the year, but I understand that due to this job offer, she had to accept it now. We want what is best for her, and she has earned that."
Contact Chris Kieffer at (662) 678-1590 or firstname.lastname@example.org.