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Adjusted Census Urban Boundary (ACUB) Statewide Review

MDOT Information on ACUB Statewide Review


At MDOT, this is the resulting area from adjusting the U.S. census decennial urban areas over 5,000 populations outward in a cooperative process by transportation agencies following federal guidelines. The roads, cities, and villages within or on the ACUB border are urban, the roads, cities, and villages outside the ACUB are rural.


David Fairchild, Transportation Planner

ACUB Mapping Application


The process of adjusting the Census Urban Areas is a cooperative process where local transportation agencies will be invited by MDOT to collectively review and adjust the Census Urban Areas outward in workshops held throughout the state. Agencies that do not attend the workshops may not have a chance to share their input.

Until the proposed 2020 ACUB boundaries are approved by the Federal Highway Administration (FHWA) and entered within the MDOT databases in 2025, the 2010 ACUB’s will continue to be in effect. The U.S. census urban areas are only used as a base for the ACUB. The ACUB determines which roads have rural or urban road designation. The ACUB is for transportation funding purposes only, it is not used for land use designation.

Adjusting the ACUB’s does not affect the population numbers or the federal metropolitan planning (PL) funding levels that are available to local agencies.

The ACUB area does affect the Act 51 county urban distribution. Adding an ACUB does not increase or decrease the total Act 51 urban funding but may affect the distribution percentages among the county’s Act 51 urban funding. Once the ACUB’s are FHWA approved, they will be shared with counties, and the counties will implement the new urban mileage into the normal Act 51 certification map process during 2025.

If your agency was removed or deleted from the U.S. Census Urban Areas, MDOT does not have any recourse to change this. MDOT and local transportation agencies must follow the FHWA guidelines and Urban Area (UA’s) released by U.S. census. Your agency would have to directly contact and work with the U.S. Census Bureau to contest the UA determination.

Smoothing is the main criteria for the adjustment process. Smoothing creates a simpler urban area shape. The goal is to prevent a road from switching back and forth between rural and urban federal funding sources and avoid confusion from irregular boundaries. The old ACUB may be used as a base for the 2020 proposed ACUB’s except where the new census urban areas extend outside the old ACUB.

The new ACUB must include all of the UA. Where modifications are proposed to the old ACUB, ask what changes occurred in the area since the last census. Does this justify an increase in urban? Are their old ACUB areas that no longer smooth the area or do not act as urban? Areas can be removed or added to the old ACUB to create the new proposed ACUB.

Agencies in attendance are encouraged to provide input to additions, deletions, or no change. After local agency input is provided, if disagreements arise, the boundary decision is up to the MDOT ACUB coordinator. If necessary, FHWA may be called in to act as an arbitrator as a last resort. Signature of the resolution document shows that local officials were offered to be part of the process and will accept the proposed ACUB.

Ideally, proposed ACUB’s can be determined in the field from data shown on maps. They should follow jurisdictional and geographical features.

In cases where a single UA extends across state borders, the contiguous states are encouraged to agree on the proposed ACUB at the state line and avoid irregularities.

To view current 2020 Census Urban Areas, visit the NFC, NHS & ACUB Web Map and select the Census 2020 - Urban Areas layer.