Why do federal prisoners have to move around to so many jails before being put in the federal prison?

This is not a normal procedure but for some inmates that have to endure it, it is called "diesel therapy". Diesel therapy is a form of punishment in which prisoners are shackled and then transported for days or weeks bouncing from county jail to county jail. This is how law-enforcement personnel gets rid of troublesome individuals by placing them on a bus to many another jurisdictions. It has been described as "the cruelest aspect of being a federal inmate." It has been alleged that some inmates are deliberately sent to incorrect destinations to prolong the diesel therapy. Voluntary surrender at the prison where the inmate will serve his time is recommended as a way of avoiding diesel therapy.