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Paste to a Routine Module :
Option Explicit
Sub Copy_Counties()
Dim StartTime As Double
Dim MinutesElapsed As String
Sheets("Master").Range("G1").Value = ""
'Remember time when macro starts
StartTime = Timer 'comment out when the elapsed timer no longer used
'Application.ScreenUpdating = False 'uncomment when the elapsed timer no longer used
Dim i As Long
Dim Lastrow As Long
On Error GoTo M
Lastrow = Sheets("Master").Cells(Rows.Count, "A").End(xlUp).Row
Dim ans As String
For i = 2 To Lastrow
ans = Sheets("Master").Cells(i, 1).Value
Sheets("Master").Rows(i).Copy Sheets(ans).Rows(Sheets(ans).Cells(Rows.Count, "A").End(xlUp).Row + 1)
'Determine how many seconds code took to run
MinutesElapsed = Format((Timer - StartTime) / 86400, "hh:mm:ss")
Sheets("Master").Range("G1").Value = MinutesElapsed
Next
'Application.ScreenUpdating = True
Exit Sub
M:
MsgBox "No such sheet as " & ans & " exist"
'Application.ScreenUpdating = True
'Determine how many seconds code took to run
MinutesElapsed = Format((Timer - StartTime) / 86400, "hh:mm:ss")
'Sheets("Master").Range("G2").Value = Timer
Sheets("Master").Range("G1").Value = MinutesElapsed 'comment out when elapsed time not required
End Sub