Value Stream Mapping vs Process Mapping

Short answer: A process map is an organized way to record all the activities performed by a person or machine — presented as a flowchart or worksheet. Value stream mapping diagrams every step involved in the material and information flows needed to bring a product from order to delivery. Toyota modified traditional process mapping into something called Material and Information Flow Analysis (MIFA), and the U.S. lean community — led by LEI — renamed and refined it as value stream mapping.

A Brief History of Process Mapping

Process mapping started in industrial engineering as the flow process chart.

Frank Gilbreth presented “Process Charts, First Steps in Finding the One Best Way to Do Work” to ASME in 1921. The tool recorded operations using a set of symbols so work could be studied and simplified.

In 1932, Allan Mogensen published Common Sense Applied to Motion and Time Study and launched the Work Simplification conferences at Lake Placid, training business people to use the process chart for improvement.

In 1947, ASME published the formal standard — Operation and Flow Process Charts — codifying the five symbols: operation (O), transportation (T), inspection (I), delay (D), and storage (S). Under this standard, a flow process chart follows a single subject — one part, one operator, or one piece of equipment — through its full sequence of steps. Three types exist: man type, material type, and equipment type.

Today, ASQ defines process mapping more broadly — “an organized way to record all the activities performed by a person or machine, with a customer or on materials.” The single-subject discipline of the ASME chart has faded; “process mapping” and “flowchart” are now treated as nearly interchangeable umbrella terms covering everything from a simple box-and-arrow diagram to a cross-functional swimlane chart.

The shift matters for this question: when someone says “process mapping,” they could mean anything from a rigorous ASME-style chart with defined symbols to a whiteboard sketch of how work moves through a department. Value stream mapping, by contrast, has a specific definition and a specific purpose.

Toyota’s Internal Modifications

Toyota inherited basic industrial engineering concepts — including process charting — in the 1940s and 1950s through a variety of sources. The tools were standard IE practice.

In the 1970s, Toyota placed a major focus on linking its Tier 1 supply base more tightly to the just-in-time system. This required mapping material and information flows from Toyota’s assembly lines to suppliers and back — something a traditional process flow chart was not built to show.

Out of that work evolved what Toyota called Material and Information Flow Analysis (MIFA). MIFA diagrams focused on aspects that traditional process flow charts did not: information flow (how each process knows what to make and when), the relationship between material movement and scheduling signals across the supply chain, and the gap between total lead time and actual processing time.

The result was a specialized version of process mapping — still following flow, but adding material quantities, information triggers, and a timeline that made the lead-time gap visible.

How It Became “Value Stream Mapping”

In the 1990s, as lean manufacturing gained traction in the United States, Toyota’s MIFA diagrams began to surface and raise questions. Western practitioners encountered the maps but had no published guide to the method.

In 1998, the Lean Enterprise Institute published its first workbook — Learning to See: Value Stream Mapping to Create Value and Eliminate Muda, by Mike Rother and John Shook. The workbook built upon Toyota’s MIFA diagrams and taught practitioners how to do a specific form of this mapping: starting from the customer perspective, following material and information flow, and using the lead-time-to-processing-time comparison to identify waste. LEI called the method “value stream mapping.”

The concept is the same one Toyota developed internally. The name, format, and teaching structure came from LEI’s workbook.