Sub locationFillDown()

    'Initialization
    Dim test, prod As Worksheet
    Set prod = Sheets("SBL3N Production")
    Set test = Sheets("SBL3N Test Environment")

    Application.ScreenUpdating = False

    'Msgbox
    MsgBox ("The process of populating locations takes a few moments. Any line items with no location will be blank.")

    'Set prod Locations

    With prod
        Dim prodLastRow As Integer
        prodLastRow = .Range("M" & Rows.Count).End(xlUp).Row 'Used Column M bc it will always be populated
    End With

    prod.Activate
    Range("V2").Value = "=IF(IF(LEN(P2)=0,E2,LEFT(P2,4))=0,99999,IF(LEN(P2)=0,E2,LEFT(P2,4)))"
    Range("V2:V" & prodLastRow).FillDown

    For Each prodCell In Range("V2:V" & prodLastRow)
        If prodCell.Value = 99999 Then
            prodCell.ClearContents
        End If
    Next prodCell


    'Set test Locations

    With test
        Dim testLastRow As Integer
        testLastRow = .Range("C" & Rows.Count).End(xlUp).Row 'Used col C bc it will always be populated
    End With

    test.Activate
    Range("Q2").Value = "=IF(AND(ISBLANK(J2),ISBLANK(K2)),99999,IF(LEN(J2)=0,K2,LEFT(J2,4)))"
    Range("Q2:Q" & testLastRow).FillDown

    For Each testCell In Range("Q2:Q" & testLastRow)
        If testCell.Value = 99999 Then
            testCell.ClearContents
        End If
    Next testCell

    Application.ScreenUpdating = True

End Sub