36 CFR § 800.14(c)  

This program alternative allows agencies to propose a program or category of agency undertaking that is exempt from further review under Section 106.  The ACHP may also propose an exemption on its own initiative. Exempted categories must be actions that would otherwise qualify as undertakings as defined in § 800.16 and the potential effects from the undertakings must be foreseeable and likely to be minimal or not adverse. Exempted categories must also be consistent with the purposes of the National Historic Preservation Act.

Interstate Highway System Exemption

Natural Gas Pipelines Exemption