Insert the USB drive. By running 'tail -f /var/log/syslog', you may see the physical assignment occur as the operating system recognizes the drive.
Failing that, after the USB drive is installed, other commands to try:
sudo fdisk -l
or:
sudo dmesg
or:
sudo blkid
Then create a mount directory, if it doesn't already exist:
sudo mkdir /mnt/usb
Then make the drive available with (where /dev/sdb1 is the physical drive assignment seen in one of the above operations), and '-t vfat' can be optional, and describes the file format of the USB drive:
sudo mount /dev/sdb1 /mnt/usb -t vfat
When done:
sudo umount /mnt/usb