Sub TimeZone()
Dim LastRow As Long, CurRow As Long
LastRow = Range("A" & Rows.Count).End(xlUp).Row
For CurRow = 2 To LastRow
Select Case Range("F" & CurRow).Value
Case "AL", "IA", "IL", "IN", "KS", "KY", "MN", "MO", "NE", "OK", "TN", "TX", "WI"
Range("M" & CurRow).Value = "Central"
Case "MI", "NC", "NY", "OH", "PA", "SC"
Range("M" & CurRow).Value = "Eastern"
Case Else
Range("M" & CurRow).Value = "Unknown"
End Select
Next CurRow