Here's a look at a 1945 publication of the Government Printing Office:
"Much has been written about process charting. This bulletin collects in one place what seems to be most significant on the subject, and at the same time summarizes actual experience from private industry and Government. It aims to put process charting into action as a practical working device in attacking management problems.
The material was initially planned for use in a series of administrative planning conferences to be conducted by the bureau of budget. The widespread interest in process charting shown by Federal agencies has led to prior publication, however, as one of the series of Bureau of the Budget Management Bulletins.
The multi-column process chart described here is particularly useful in analyzing procedures involving more than one unit or section of an agency organization."
The multi-column chart may be recognized by some readers as what is more commonly referred to today as a swimlane chart. Also, take a look at the form distribution chart on page 4 - this is a precursor to the current multi-line flowchart.