This dataset consists of National Park Service (NPS) tract boundaries (public and private) within the Santa Monica Mountains National Recreation Area (SMMNRA) and major local parkland areas outside the SMMNRA boundary. NPS tracts do not necessarily correspond to assessor parcels. Contiguous parcels owned by one entity are grouped into one tract. Contiguous parcels where development existed prior to park establishment in 1978 are grouped into large tracts. Parkland outside the SMMNRA boundary is mapped on an opportunistic basis and is not complete. Property boundaries were initially drafted by hand on 1:24000 USGS topographic maps and later digitized by private contractor. The current geography has been edited to better register with Los Angeles County and Ventura County Assessor maps.

In 2012, geography was reconstructed by GIS Technician, Luis Aguilar, using 2010 Los Angeles County and Ventura County parcel data. Parcel polygons were edited to conform to tracts within the NRA. Outside the NRA, park land polygons were imported from previous tracts data. Road gaps in parcels were collapsed to centerline so there is a continuous fabric within the NRA boundary. Attributes and tract boundaries were checked against official NPS sources and current parcel data. Work was completed in 2014 and data imported into file geodatabase with topology.

Data attributes and geography are updated on an ongoing basis to the best of NPS' ability, but due to volatility of land ownership in this area and complexity of merging two different property delineation systems (i.e. assessor parcels and NPS tract system), confirm information derived from this data with other sources when accuracy is critical. NPS property current as of February 2018. Updates and edits are recorded in online edit log on SAMONet GIS (https://sites.google.com/a/nps.gov/samo_gis/home/gis-data).

Dates for NPS acquisition were added to the Date_Acquired field by Morgan Vahradian and Denise Kamradt on 10/5/2016 based on Excel spreadsheet maintained by Melanie Beck. The field also includes a few other park agency land acquisition dates, but the data are not complete. All park acquisition dates will be added as time permits. Check for revised version.