All of the Missouri State Penitentiary's 1,350 inmates were expected to be in their new cells in eastern Jefferson City by Wednesday night.
By Thursday, Missouri Corrections officials expected to have no inmates imprisoned on the MSP grounds for the first time since 1836.
The first inmates to be transferred arrived at the new Jefferson City Correctional Center about 6:30 a.m. Wednesday.
"Inmates at MSP are being completely searched, placed in shackles, placed on the buses and then transported out here," Corrections Department spokesman John Fougere said in an interview in the new prison's administration building. "We expect it to go, probably, into the early evening, and then we should be completed."
Citing security reasons, Fougere declined to release the number of buses being used or the number of inmates being placed on each one.
"I can tell you it will be a steady stream throughout the day," he said. "We're grateful for the partnership with area law enforcement, to help us with things like escorts and clearing the roads."
Jefferson City Police Capt. Ray Bledsoe said 11 officers were assigned to a special detail, "working intersections, making sure they get through. We don't want those buses to have to wait at a light."
Cole County Sheriff George Brooks said his deputies and some Missouri State Highway Patrol troopers were providing escorts for the buses they drove from MSP to the new prison.
"It's going rather smoothly," Brooks said. "It's going as planned."
Both Bledsoe and Brooks said the Corrections Department had been working with area law officers for at least the last couple of weeks, making plans and finalizing details for today's inmate transfer.
Fougere said Corrections officials chose Wednesday for the move, making "sure that everything was all operational, and we felt confident we could move over 1,300 maximum security offenders into this institution."
Corrections Department Emergency-Squad members from 18 Missouri prisons were called in to help with the transfer.
The $128 million new prison can house a maximum of 1,996 inmates mostly in two-inmate cells. MSP's design capacity was 1,800.
Department officials have said the new prison's modern design will make it a safer, more manageable place than MSP, which has been the oldest continuously operated prison west of the Mississippi River.
Fougere said it will take about 45 days for the department to complete the move of "equipment and other things" from MSP to the new prison.
Around Nov. 1, the department will turn control of the old site to the state Office of Administration, which is handling redevelopment plans for the 148-acre site just east of downtown Jefferson City.
Milestones in MSP history
Some important dates in the history of the Missouri State Penitentiary
Information taken from the book "Somewhere in Time: 170 Years Missouri Corrections."