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Section 106 review: the NHPA process, step by step

Section 106 of the National Historic Preservation Act requires a federal agency to weigh a project's effects on historic properties, and let the Advisory Council on Historic Preservation (ACHP) comment, before it funds or licenses the project[1]. Under 36 CFR part 800, that means consulting the State Historic Preservation Officer (SHPO)[2][3].

By Ilya Volodarsky. 16 sources, last read on . This page explains the law; it is not legal advice.

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    Describe the project and ePlan drafts the Section 106 consultation letter with the undertaking, area of potential effects and identification steps; every fact it can't confirm is marked for you.

    ePlan vs. by hand

    How ePlan compares to drafting a Section 106 Consultation Letter by hand

    The same document, two ways to a first draft.

    ComparedePlan.aiBy hand
    Survey and map filesePlan.aiUpload survey reports as PDF or Word and the area of potential effects as a shapefile, GeoJSON or KML, up to 50 MB eachBy handCopying survey findings and map references into the letter by hand
    Starting pointePlan.aiA consultation letter that follows a reference letter's structure, with your project facts filled in and gaps markedBy handYour office's last SHPO letter, edited by hand
    Precedent researchePlan.aiA research agent searches agency project pages, CEQAnet, the Federal Register, eCFR and EPA's EIS database for your project and up to two analog projectsBy handSearching each agency site and PDF library by hand
    Missing factsePlan.aiEvery fact ePlan can't confirm stays a highlighted [INSERT] placeholder until someone fills itBy handGaps surface in review, or not at all
    Cost to startePlan.aiScoping letters are free. EAs, EIRs and decision memos are on Max at $199 a monthBy handStaff or consultant hours for every draft

    ePlan.ai as of October 2026. “By hand” means a Word template, past documents and agency PDFs. Your team reviews, edits and signs every draft.

    The Section 106 process: four steps in 36 CFR part 800

    Historic properties are listed in or eligible for the National Register, including places important to tribes and Native Hawaiian organizations[4]; most are 50 or more years old[3]. An activity that cannot affect them ends the review[5].

    On July 24, 2026 the ACHP voted to send a draft rewrite of part 800 for White House (OIRA) review. It has not been published for comment, and part 800 is unchanged since 2016[10][11][2]. The steps:

    • Initiate: confirm the undertaking, find the SHPO or THPO, invite consulting parties[5]
    • Identify: set the area of potential effects, review records, run surveys, apply the National Register criteria[6]
    • Assess: decide whether the undertaking would harm each property's integrity[7]
    • Resolve: avoid, minimize or mitigate adverse effects, usually in a memorandum of agreement[8]

    What is a SHPO? Who takes part in Section 106

    The SHPO runs the state historic preservation program; a THPO does so on tribal lands[4]. The agency consults them, invites tribes that may attach significance to affected properties, and owns every finding, even one a consultant writes[12][5].

    On the Milton-Madison Bridge over the Ohio River, FHWA planned in 2009 to replace a National Register-eligible 1929 span, closing the crossing for a year. Consultation with both states' SHPOs, the towns and preservation groups produced a memorandum of agreement with a free ferry. When the contractor cut the closure to 10 days, the parties dropped the ferry and kept heritage tourism funds[13].

    How long does SHPO review take?

    The SHPO/THPO has 30 days; if it does not respond, the agency may move on or consult the ACHP instead[5]. A finding of no historic properties affected, or of no adverse effect, stands if no one objects within 30 days[6][7].

    The ACHP reviews disputed findings within 15 days, extendable by 15[7]. For an adverse effect, reported through e106, it has 15 days to decide whether to join[8][14].

    Section 106 review and NEPA: 36 CFR 800.8

    Coordinate Section 106 with NEPA early; an adverse effect alone does not require an EIS. An agency may use its EA or EIS for steps 800.3 to 800.6 instead, if it tells the SHPO/THPO and ACHP first and meets 800.8(c)[15].

    Outline

    Section 106 consultation letter: what to include

    Based on 36 CFR part 800's initiation and documentation rules[5][16]. A categorical exclusion does not end Section 106 review, ESA section 7 often runs alongside it, and HUD and FEMA reviews cover both.

    1. Undertaking

      The project, its federal funding, permit or license, and who is consulting, with maps and photographs[4][12][16].

    2. Area of potential effects

      Where the project may change the character or use of historic properties, on a map[4][6].

    3. Historic properties

      Records and surveys reviewed, each property found, and your National Register eligibility recommendation[6][16].

    4. Effects and finding

      Effects on each property and why the criteria of adverse effect do or do not apply[7][16].

    5. Consulting parties and the public

      Tribes, local governments and others invited, their views, and how the public took part[5][16].

    6. Request

      What you ask the SHPO/THPO to review or agree with in its 30 days[5][7].

    Sources

    Where each statement comes from

    Show all 16 sources
    1. [1]54 U.S.C. 306108 - Effect of undertaking on historic property (NHPA section 106). United States Code, 2024 edition (GovInfo). Read October 2, 2026.
    2. [2]36 CFR part 800 - Protection of Historic Properties. Electronic Code of Federal Regulations (eCFR), current. Read October 4, 2026.
    3. [3]Protecting Historic Properties: A Citizen's Guide to Section 106 Review. Advisory Council on Historic Preservation, January 2021. Read October 2, 2026.
    4. [4]36 CFR 800.16 - Definitions. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.
    5. [5]36 CFR 800.3 - Initiation of the section 106 process. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.
    6. [6]36 CFR 800.4 - Identification of historic properties. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.
    7. [7]36 CFR 800.5 - Assessment of adverse effects. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.
    8. [8]36 CFR 800.6 - Resolution of adverse effects. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.
    9. [9]36 CFR 800.7 - Failure to resolve adverse effects. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.
    10. [10]ACHP Votes to Move Forward with Notice of Proposed Rulemaking. Advisory Council on Historic Preservation, July 24, 2026. Read October 4, 2026.
    11. [11]Pending EO 12866 Regulatory Review: RIN 3010-AA10, Amendments to the Implementing Regulations for Section 106 of the National Historic Preservation Act (proposed rule). Office of Information and Regulatory Affairs, RegInfo.gov, July 28, 2026. Read October 4, 2026.
    12. [12]36 CFR 800.2 - Participants in the Section 106 process. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.
    13. [13]Success Story: Creative Mitigation Heralded as Success for Local Economy (Milton-Madison Bridge, KY-IN). Advisory Council on Historic Preservation. Read October 3, 2026.
    14. [14]Protecting Historic Properties (Section 106 overview). Advisory Council on Historic Preservation. Read October 2, 2026.
    15. [15]36 CFR 800.8 - Coordination with the National Environmental Policy Act. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.
    16. [16]36 CFR 800.11 - Documentation standards. Electronic Code of Federal Regulations (eCFR), current. Read October 2, 2026.

    Written by

    Ilya Volodarsky

    Ilya Volodarsky founded ePlan.ai. He co-founded Segment and is co-founder and CEO of Wildfires.org.

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    • The letter that opens consultation with the SHPO or THPO, or asks it to review a finding. There is no federal form; some SHPOs and THPOs have their own.

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