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Traffic Records

Model Minimum Uniform Crash Criteria



MMUCC 6th Edition


The Model Minimum Uniform Crash Criteria, also known as MMUCC, is a voluntary guideline that represents a minimum, standardized set of data variables to describe motor vehicle traffic crashes, which could be used to identify traffic safety problems and design countermeasures to improve traffic safety nationally and in each state. MMUCC was first developed in 1998 and was updated in 2003, 2008, 2012, 2017, and 2024.


Law enforcement officers collect information from motor vehicle traffic crashes using police crash reports. This information describes the characteristics of the events, vehicles, and people involved in the crash. Ideally the data from each PCR is then entered into a state’s centralized database, inspected for quality, amended if necessary, reported, and analyzed by a range of stakeholders.

Although all 50 states, the District of Columbia, and several U.S. territories collect data about motor vehicle traffic crashes, there are significant differences in the way that such data is reported. Definitions, the number and type of data fields, the number and specificity of selections, and the threshold for data collection often vary from jurisdiction to jurisdiction and from state to state. This makes it especially difficult to compare data across state and local agencies, between states, and between states and the federal government. Determining larger patterns and timely trends in motor vehicle traffic crash data becomes much more challenging under these circumstances.

Properly identified and defined vocabulary are necessary for a common language in the traffic safety community. The MMUCC guideline is primarily based on another national standard, the American National Standards Institute (ANSI) D.16-2017 Manual on Classification of Motor Vehicle Traffic Crashes. ANSI D.16 identifies, defines, and classifies the specific terminology associated with motor vehicle traffic crashes. The MMUCC guideline conveys the minimum data elements and attributes using the terminology and concepts from the ANSI D.16 that a state’s PCR should incorporate for nationally uniform data collection. When used together, the two documents provide the states with the necessary information to collect motor vehicle traffic crashes in a uniform manner. 

Aligning to MMUCC

A method for comparing a state’s current set of data elements and attributes with those recommended in this sixth edition of MMUCC is included in Chapter 12: Aligning to MMUCC. This chapter describes a method for making the comparison and identifies rules that NHTSA considers when mapping. The intent is to help states identify areas in their data collection systems that are not aligned to MMUCC, and then prioritize those data elements and attributes requiring modification when the state or locality updates its crash report. States can request a new state-to-MMUCC alignment report or additional information by contacting their NHTSA regional office.

When updating a crash system, NHTSA encourages states to consider the relationships between the state’s crash system and NHTSA’s records-based crash data systems, FARS and CRSS. NHTSA uses FARS and CRSS to identify highway safety priorities, measure trends, and assess the effectiveness of motor vehicle safety standards and highway safety programs. The MMUCC 6th Edition, FARS, and CRSS have made significant efforts to reduce inconsistencies. Data elements, attributes, definitions, and guidance have been harmonized when appropriate across the platforms. States that increase their alignment to the MMUCC 6th Edition will greatly assist state FARS reporting in the traffic records performance measures timeliness, completeness, and uniformity.

Many states use electronic data transfer to share motor vehicle crash data from state data repositories with NHTSA. NHTSA uses EDT to advance real-time data collection and transfer, enable more timely decision-making, reduce the burden of data collection, improve data quality, and make data available sooner. Ultimately this supports the FARS and CRSS programs, which align to many MMUCC data elements. When a state aligns more closely to MMUCC, less work is needed to translate between the state data elements and NHTSA’s data elements, and sharing data is easier. States can request additional information about EDT by contacting their NHTSA regional office.

Information Exchange Package Documentation (IEPD) serves as a comprehensive package outlining the rules and standards governing the exchange of information between systems. Its purpose is to support consistency and interoperability in data sharing. NHTSA has created a MMUCC 6th Edition IEPD to facilitate the sharing of crash data based on the MMUCC 6th Edition.

New Features

Below are important highlights of the sixth edition. 

  • When applicable, implementation suggestions have been added to the data elements to ease electronic data collection efforts.
  • New Chapter 3: System-Populated Data Elements provide tracking information on the status of a crash record in the workflow and enable system linkage with other data systems. 
  • Data elements that are only applicable to drivers have been organized in the new Chapter 6: Driver Data Elements.
  • The MMUCC 6th Edition emphasizes data integration with other data standards. Data elements that can be obtained from another State data system are in the new Chapter 10: Traffic Records Data Integration. 
  • A new Chapter 11: Designing User-Centered Crash Reporting Systems highlights best practices for more efficient and effective electronic data collection. 
  • NHTSA changed the MMUCC 6th Edition mapping rules to be more flexible and enable more state data elements to align with MMUCC and facilitate electronic data sharing. See Chapter 12: Aligning to MMUCC for details.
  • Discrepancies between MMUCC and NHTSA’s FARS and CRSS data systems have been substantially reduced. By doing so, states and NHTSA will collect the same information using the same formats. This will benefit states wishing to participate in NHTSA’s EDT protocol.

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Future Updates

MMUCC is generally updated every 5 years. The next update is tentatively scheduled for 2029. In the years preceding the next update, traffic records experts and the public will have opportunities to provide suggestions for improving MMUCC for the seventh edition.

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The National Driver Register and Traffic Records Division, within NHTSA’s National Center for Statistics and Analysis, manages MMUCC.

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