It appears the 19-year-old tried to take evasive actions but crashed into a guardrail and then a highway sign pole. He died at the scene.
Johnson was on leave but returned to the base to pick up a new pair of pants and gloves to attend a Marine Corps Ball with his girlfriend in Las Vegas this weekend.
"Even before he left, I told him to sleep at the base; I didn't have a good feeling about this," said girlfriend Kylee Halladay. But Johnson left Twentynine Palms late Tuesday night and headed back to Fresno to be with Halladay, a student at California State University, Fresno.
They'd spent Tuesday afternoon together; he walked her to class then picked her up afterward and took her to the mall where he bought her a promise ring.
The couple dated for a few months when they attended Enochs High School in Modesto. They reconnected earlier this year and have been dating since July, using Facetime every night to stay connected when they were apart.
Halladay described Johnson as kind, genuine, loyal and funny.
"He always filled everyone with laughter and yes, he did show off how strong he was by using me as a weight," Halladay said. "He was so confident in everything he did and he was so proud to be a Marine."
She said she awoke at 4:48 a.m. on Wednesday after dreaming about Johnson and was panicked to find he had not yet returned.
She called his cell phone multiple times with no response and at about 5 a.m. her calls began going straight to voicemail.
Two of the responding California Highway Patrol officers at the scene of the crash on Highway 99 near Traver just north of Visalia were military veterans.
A sergeant and an officer quickly established that Johnson was an active duty Marine, and made it a point to drape an American flag over his body, replacing the yellow blanket that is typically draped on crash victims.
"That young man, he deserved more and we wanted to give him that," CHP Sgt. Ryan Pedersen said.
Pedersen, who served nine years in the Navy and is a member of the CHP honor guard, made the call to use a flag but said fellow CHP officer Michael McWain, a former Marine, suggested it.
CHP officers don't carry American flags in their squad cars, so Pedersen had an officer deliver one from the Visalia office to the accident scene just south of Merritt Drive on Highway 99. CHP offices keep flags on hand, because if a CHP officer dies in the line of duty, it's an option to drape the body with a flag.
Meanwhile, McWain took the step of contacting the Marines and stayed with the body as it was transported to Sterling Smith Funeral Home in Tulare and at the mortuary until the end of his shift. By then, representatives of the Marines were on their way to Tulare.
Johnson was an Armorer with the Marine Unmanned Aerial Vehicle Squadron unit.
He played football and baseball at Enochs High and football for the Modesto Brancos Youth Football team.
He is survived by his parents and three young younger brothers, Halladay said.
--The Fresno Bee's Lew Griswold contributed to this report.