the original code was

'remove before and after blanks via TRIM function
Range("D2", Range("C2").End(xlDown).Offset(0, 1)).FormulaR1C1 =
"=TRIM(RC[-1])"
Columns("C:C").Value = Columns("D:D").Value

I ran the code without the Columns("C:C").Value = Columns("D:D").Value
and it worked fine
but when included, if fails at the 16th sheet.

I know I could do cell.value = trim(cell).value but I
find .FormulaR1C1 to work faster.