Excel Autofill Question

[Zero85]

I'm working on a file with over 30,000 rows. I need to fill in columns with unique ID's and employee names however not all the cells are filled out for each person. If I try to autofill, Excel overrides the data. I need Excel to stop its autofill feature as soon as a new row with content containing data is found.

 

[Fluff]

Maybe something along the lines of

Sub Zero85()
   With Range("B2", Range("A" & Rows.Count).End(xlUp).Offset(, 1))
      .SpecialCells(xlBlanks).FormulaR1C1 = "=r[-1]c"
      .Value = .Value
   End With
End Sub

This will fill blank cells in col B with the value from the row above