How long is the drive back to Portland?
From where ?
Or, if you have a lead foot and no traffic problems, 3 hours.
I drive Florence to Portland airport in about 3 hours and 15 minutes. The times that I clocked that were under perfect conditions. MapQuest estimates that same drive at 3 hours and 12 minutes and Portland itself as 3 hours and 27 minutes. The Portland area is subject to rush hour traffic and the times that I have been in rush hour I did not clock it but seems like that added about 15 or 20 minutes. Highway 126 is a winding 2 lane road and so can be slow in bad weather or at night. Highway 126 is sometimes worked on in summer and they flag you through on one lane. When they do this they warn of 20 minute delays but usually it is only about 5-10 minutes delay.