The National Park Service determines which properties meet NHL criteria and makes nomination recommendations after an owner notification process.
[1] The Secretary of the Interior reviews nominations and, based on a set of predetermined criteria, makes a decision on NHL designation or a determination of eligibility for designation.
This designation provides indirect, partial protection of the historic integrity of the properties, via tax incentives, grants, monitoring of threats, and other means.
[2] NHLs are also included on the National Register of Historic Places (NRHP), which are historic properties that the National Park Service deems to be worthy of preservation.
The primary difference between an NHL and a NRHP listing is that the NHLs are determined to have particular national significance, while other NRHP properties may be deemed significant at the local or state level.