A historic resource is a building, structure, object, site, landscape, or a grouping of these types of properties (known as a historic district) that is significant in history, architecture, archaeology, engineering, or culture. Historic resources are usually more than 50 years old and qualify for listing in a local, state, or national historic register based on their association with significant historic events, individuals, or architectural design or construction techniques.

Identifying Historic Resources

Historic resources in San Mateo are identified in multiple ways. Some are identified when they are officially listed in national, state, or local historic registers, which is usually done by property owners. Historic resources are also identified through surveys and other evaluations prepared by qualified architectural historians that are completed for local planning and environmental review.

The National Register and California Register

The National Register of Historic Places (National Register) is a federal-level inventory containing significant resources worthy of preservation. The California Register of Historical Resources (California Register) is a parallel state inventory that includes many of California’s significant built and archeological resources. The National Register and California Register are similar, including in their evaluation criteria: each includes resources associated with significant events, individuals, or architectural design or construction techniques. Archaeological resources can also be significant for the information they provide on history or prehistory. Nominating a property to either the National Register or California Register requires review and approval by the California Office of Historic Preservation (OHP) and the State Historical Resources Commission (SRHC). OHP’s website provides additional details on the nomination process for the National Register and the California Register.

Difference Between “Listed” and “Eligible” Resources

A property or properties can be deemed eligible for either the National Register or the California Register if the applicable criteria outlined above are met. Properties or districts can be deemed eligible for either register through an evaluation by a qualified architectural historian and can be listed through the nomination process described above. An eligible historic property will not be listed on the California or National Register over an owner’s objection. For a district nomination, the eligible district will not be listed on either register if a majority of property owners object. A historic resource, whether it is eligible or listed, is subject to review under the California Environmental Quality Act (CEQA), should it be impacted by a project that results in a physical change in the environment.  

Historic Districts

A historic district is a significant grouping of buildings, structures, and/or objects that convey significant patterns in the development of San Mateo, California, or the United States. Historic districts come in many shapes and sizes, but each district contains contributing properties that share a significant historic context, plan, and/or aesthetic. Historic districts become listed in the California Register and National Register through a similar process as individual properties. One important difference is that a historic district cannot be listed over the objection of a majority of the property owners in the district. However, the district would still qualify as an eligible historic district, which is treated the same as listed historic districts with respect to state- and federal-level project review, including environmental review under CEQA.

Contributors within Historic Districts

When a historic district is first evaluated, the properties within the district boundaries are identified as either contributors or non-contributors. Contributors are the properties that date to the district’s period of significance and still retain enough of their historic character to convey the district’s historically important character. In contrast, non-contributors are not closely connected to the district’s significant historic qualities. This might be because they were built outside of the period of significance, or they may have been altered so much that have lost their connection to the district’s significance. The number and arrangement of contributors within a district can vary from example to example. In some cases, a district with many non-contributors can still qualify for listing in a historic register, so long as the contributors that do exist are able to convey the district’s significant historical or architectural character.

Protections Afforded to Historic Resources

Eligible and listed historic resources in San Mateo, including individual properties and historic district contributors, are subject to certain protections and special review under the local Historic Preservation Ordinance and CEQA. Determination of eligibility or listing for the National Register or California Register results in legal protections for the property or district. For example, environmental review may be required under CEQA if a project may cause a substantial adverse change to eligible or listed historic resources through demolition or alteration. Historic resources are also subject to additional codes including the City’s Historic Preservation Ordinance (Municipal Code Section 27.66).