If you want all of your usb drives to follow a defined drive letter mapping try
USB DLM It is also handy when you connect to a network that has mapped drives. You can set your USB drives to avoid any drive mapping. This has caused no end of grief ...either the network drive doesn't get mapped or the USB drive just doesn't play. Now with USBDLM installed first usb drive gets J, second K, third L and the network drives are sprayed around these
