I know that anesthsiology residency has traditionally involved a pgyI clinical base year and 3 years of anesthesia. Now, I have heard that there is a move toward 4 year catagorical residencies, but I don't know hopw many are going that way. With the 1+3 programs, how does one do this? Do you match into anesthesia as an MS4, or do you go to a prelim position and match during that year? Do you have to do the pgy1 year at the program in which you will be doing CA1-3? Or, could you match into anesthesia in city X and do your pgy1 year in city Y? Thanks.