CCLCM: two summer rotations required (basic science rotation starts mid-July before first year, clinical science rotation starts in mid-July before second year)
Columbia: optional, start date June or July
Cornell Tri-I: required, start date July 7
Dartmouth: required, start date June 16
Emory: optional, early June
Harvard: required, start date July 7
Johns Hopkins: optional (and not encouraged), flexible start, ~30%
MSSM: required, start date June 1
Northwestern: required; start date July 1
OHSU: optional but discouraged
UCSD: Optional; (start date early June?)
UCSF: optional, start date July 1
University of Iowa: optional (but strongly encouraged); start date flexible, but definately before July 1; 50-80%
University of Michigan: Optional; start date June 2; ~10%
University of Minnesota: Required; start date July 1
University of Pennsylvania: Optional; (start date flexible, not sure about absolute latest); ~20%
University of Pittsburgh: Required; starts Jun 1
UTSW: Required; (start date unknown, some time in June)
Washington University: Optional; start date June 16; ~50%
UW (Seattle): Required; start date ~July 1
University of Wisconsin: Optional; (start date unknown); ~10-20%
Virginia Commonwealth: Required; starts ~3rd week of June
gstrub (if you read this), I'm 99% sure the summer rotation is required, right?