PCTA Interactive Map Layer Descriptions

This guide contains information about each of the layers used in PCTA's Interactive Map, such as source info, and tips on how to use them.

If you're looking for the Interactive Map, use the link below:


Pacific Crest Trail (group)

Mile Markers (2023)

These points represent markers every half mile of the PCT. The data only appears when zoomed in. The data is derived from a combination of GPS surveys and GIS modeling. This is currently the most accurate mile marker dataset for the PCT, despite potential differences from existing 3 rd  party applications and guidebooks. This data was created and is maintained by PCTA. Mile markers are re-created on a yearly basis in January.

Tenthmile Markers (2023)

These points include markers every tenth of a mile on the PCT. They only appear when zoomed in far. The data source is the same as the regular mile markers, and they are released on the same schedule.

Mile Markers (2022)

See the 2023 Mile Markers description. This is the 2022 version of PCTA’s mile marker dataset. Try comparing to the 2023 dataset to see the minor differences that affect the calculated length of the PCT each year.

PCTA Regions

These colored lines represent the different management regions that PCTA uses to administer the trail. There are regional staff devoted to each of these regions. The data is hosted by PCTA.

PCT Letter Sections

This data displays the lettered PCT sections that are often referred to in guidebooks and phone apps. This data is hosted by PCTA.

PCTA Centerline

PCTA's "center line" data is the most accurate representation of the location of the PCT available. This data was originally created using  Halfmile 's highly accurate data, and has been updated annually with any changes in the route that occur. It was created and is maintained by PCTA. The data is released each January, along with new Mile Marker points.

Data in this layer varies in accuracy for different regions of the trail, but most of it is highly accurate.

Recreation (group)

Trail Towns and Resupply Locations

This point data represents trail towns and other relevant resupply points along the PCT. It may not include all possible resupply locations. It was created and is maintained by PCTA.

USFS Recreation Sites

This layer displays US Forest Service data for National Recreation Opportunities. This includes facilities like trailheads, campgrounds, boat launches, and more. This is a subset of that data for the 25 National Forests that the PCT passes through. For recreation opportunity data for the rest of the U.S., see  https://www.fs.fed.us/ivm/ 

Note that the completeness of this data may be different across different National Forest units. This data is provided by the US Forest Service.

Washington SnoParks

SnoParks are cleared parking areas that are in close proximity to groomed and backcountry trails. The data is provided by Washington State Parks and Recreation.

National Forest System Trails (USFS)

This layer contains trails managed by the US Forest Service, on units that the PCT passes through. Note that the completeness or availability of trails data varies across Forests.

National Park System Trails (NPS)

This layer contains trails managed by the National Park Service, on units that the PCT passes through. Note that the completeness or availability of trails data varies across different Parks.

State Park System Trails (CA)

This layer contains trails managed by the California State Parks, on the 5 units that the PCT passes through. Note that the completeness or availability of trails data varies across different Parks.

National Trails Intersecting PCT

This dataset includes portions of National Scenic Trails (NSTs) and National Historic Trails (NHTs) that the PCT crosses. The data was originally pulled from authoritative sources, and then was clipped to the CA/OR/WA state boundaries for display in the web map.

Permit Areas

This layer contains polygons representing areas where permits are required along the PCT. The popups contain information about the permit required, and a link to the agency unit's website. This layer is maintained by PCTA.

Lands and Boundaries (group)

Wilderness Areas

This layer contains polygons representing federally designated Wilderness areas in CA, OR, and WA. This data was originally provided by  Wilderness Connect , the authoritative source for wilderness information online. Three California State Wilderness areas were added to this dataset, and regulations for All Visitors, Overnight Visitors, and Stock Users added. The data is now maintained by PCTA in this form.

National Monuments

This polygon dataset includes National Monuments managed by the BLM, USFS, and NPS within 4 miles of the PCT. Data originated from publicly available layers from these 3 agencies. It was created and is maintained by PCTA.

Special Area Designations

This layer contains Special Area Designation lands managed by NPS, BLM, and USFS in CA, OR, and WA. It was created and is maintained by PCTA.

Definition of Special Area Designation – A legislated formal area designation of areas unique for their special characteristics and the opportunities they offer. In addition to designated wilderness and wild and scenic rivers, they include these National Historic Landmarks (NHL), National Volcanic Monuments (NVM), National Historic Scenic Areas (NHS), National Recreation Areas (NRA), Scenic Recreation Areas (SRA), National Scenic Areas (NSA), National Preserves (NP), and National Monuments (NM). 

Land Manager (PADUS)

PCTA’s copy of USGS Protected Areas Database of the United States (PAD-US) Fee Manager data showing land management in the states of California, Oregon, and Washington. This data was created by USGS to provide assessment of the conservation/protection status of lands in the United States and serves as the most complete compendium of nation-wide land management boundaries. For more information on the PAD-US data, see  https://www.usgs.gov/programs/gap-analysis-project/science/pad-us-data-overview 

Ranger District Boundaries

PCTA’s hosted version of USFS Ranger Districts from Region 5 and 6, as well as the Humboldt-Toiyabe National Forest. This data originated in the USFS Enterprise Data Warehouse (EDW).

National Forest Administrative Boundaries

This is PCTA’s copy of USFS Forest Administrative Boundaries for Regions 5, 6, and the Humboldt-Toiyabe National Forest. See the following from the U.S. Forest Service’s description:

An area encompassing all the National Forest System lands administered by an administrative unit. The area encompasses private lands, other governmental agency lands, and may contain National Forest System lands within the proclaimed boundaries of another administrative unit. All National Forest System lands fall within one and only one Administrative Forest Area. Click this link for full metadata description:  Metadata 

Indigenous Territories (native-land.ca)

These polygons are the indigenous territories mapped by  Native Land Digital  in California, Oregon, and Washington. Periodically,  PCTA does a manual load of the Native Land Digital data, so this dataset may lag behind the daily updates occurring on Native Land Digital’s version of the map. These indigenous territories are meant to serve as a starting point to learning about the indigenous peoples whose ancestral and current lands many people on the west coast occupy. Please check out the Native Land Digital website for more information on ways to use this data, dig deeper, or suggest changes.

Below is the disclaimer provided by Native Land Digital:

This map does not represent or intend to represent official or legal boundaries of any Indigenous nations. To learn about definitive boundaries, contact the nations in question. Also, this map is not perfect -- it is a work in progress with tons of contributions from the community. Please send us fixes if you find errors. If you would like to read more about the ideas behind Native Land or where we are going, check out the  blog . You can also see the  roadmap .

Counties

This layer by ESRI: USA Counties (Generalized) provides 2017 boundaries for the counties of the United States in the 50 states and the District of Columbia.  The linework has been generalized for increased performance and best viewed at smaller scales.

Wild and Scenic Rivers Intersecting PCT

This line data represents segments of Wild and Scenic Rivers that the PCT touches or crosses (intersects). The Wild and Scenic Rivers System was created by Congress in 1968 to preserve certain rivers with outstanding natural cultural and recreational values for current and future generations. This dataset is hosted by PCTA, created from USFS data. For more information on Wild and Scenic Rivers, visit  https://www.rivers.gov/wsr-act.php 

USA Census Populated Places

This layer managed by ESRI represents populated place areas within the United States that include both incorporated places and census designated places identified by the U.S. Census Bureau.

Public Land Survey System

The public land survey system (PLSS) divides land into 6-mile-square townships, which are then subdivided into 36 one-mile square sections. These are often subdivided into quarter sections, and quarter-quarter sections. This system of dividing lands was originally designed to yield these predominantly uniform parcels. The PLSS was introduced to divide up the original federal public domain lands, which included land ceded to the government by the original states, land acquired from foreign governments, and land stolen from indigenous people. The system is often used to describe locations especially within the federal governmental land management agencies, and for legal descriptions of land boundaries.

The Bureau of Land Management hosts this nation-wide PLSS dataset. Look here for more information:  https://pcta.maps.arcgis.com/home/item.html?id=90eae2e0e8314156b893f471404a4a8f 

Natural Resources (group)

Passes, Gaps, and Similar Features

This dataset includes named mountain passes, gaps, and similar features found along the PCT. This was originally created to capture locations of classic hiking passes in the Sierra Nevada, but was expanded to include other types of passes such as road and highway crossings with "pass" in their names, and other features that represent the same geographic feature, but use other words. Passes, gaps, summits, saddles, notches, cols, and other features named on USGS topographic maps were included. This data is hosted by PCTA.

Watersheds (USGS)

These polygons represent boundaries of different drainages along the PCT. All areas within one watershed boundary will flow into a common water body, like a stream, river, or lake. This is PCTA's copy of the USGS data, selecting for only the watersheds that the PCT intersects.

Ecoregions - Level III (EPA)

Per the Environmental Protection Agency (EPA): "Ecoregions are areas where ecosystems (and the type, quality, and quantity of environmental resources) are generally similar." This data is hosted by ESRI. See  here  for more information

PCT Corridor Elevation Ranges

This layer represents the PCT corridor by elevation, categorized by 1,000ft increments. Note that gradients between elevations are not shown, it's all or nothing by 1k ft. The layer was built based on 30 meter Digital Elevation Model (DEM) data, categorized by elevation range, and vectorized.

Geology (USGS)

This layer contains data from the US Geologic Survey (USGS) compiling state-level geologic maps into this nationwide dataset. It describes the lithology, and other categorizations for the geologic areas shown as polygons. For technical information, visit this  site .

Fire (group)

Fire Reports (IRWIN)

This layer provides a near real-time view of the data being shared through the Integrated Reporting of Wildland-Fire Information (IRWIN) service. IRWIN provides fire information created collaboratively between participating wildfire organizations, including federal, state, and local agencies. The popups are configured to display attributes like the wildfire name, discovery date, type, acres burned and more. There are also various helpful links in each popup. The twitter link will search the incident name on Twitter, where there is often recent tweets about the fire. The Search for Local Fire Resources links perform searches for the county’s emergency management resources based on the county the fire is in. Additional Resources contains a link to the NWS weather forecast at the fire’s location, a link to FlightRadar24 (which shows real-time aircraft flight paths), and Windy (which shows an interactive map displaying wind movement).

Satellite Thermal Hotspots and Fire Activity (MODIS and VIIRS)

These represent the approximate locations of heat detected by NASA Satellites. These hotspots usually indicate the presence of actively burning wildfire, though they can  erroneously pick up large smoke plumes in the night as wildfire hotspots . The satellites take snapshots of hotspots as they pass over the earth, over 3 times per day. You can click or tap on a hotspot for detection age and additional info.

The sensors work by capturing emission of mid-infrared radiation, and using algorithms to determine if the radiation is caused by fires. Each satellite processes this on a pixel-by-pixel basis, with MODIS pixels representing 1km on the ground, and VIIRS representing 375m on the ground. This means that if there are multiple fires within that 1km or 375m box, only one hotspot point will appear. These points are indicative only, are not curated by experts, and are subject to horizontal accuracy issues and errors (especially with large hot plumes of smoke). Read more about issues you might encounter  here .

Update Frequency: In mid-latitudes, MODIS and VIIRS readings are gathered and calculated more than 3 times per day. Because the data is derived from instruments aboard satellites that pass over the earth continuously, the time that overpasses occur for a given area varies by satellite, and by day. For more information on the hot spot layers, it is recommended that you see  FIRMS FAQ .

2024 Wildfire Perimeters (NIFC)

This layer shows the estimated burned area on wildfires determined by the incident management team. This service displays the current calendar year’s fire perimeters to-date. These are generally based on overnight observations from aircraft with infrared sensors ( NIROPS ) but will usually update each day for large fires before 10:00AM Pacific Time. For more information on the current year’s Wildfire Perimeters data, see:  https://nifc.maps.arcgis.com/home/item.html?id=7c81ab78d8464e5c9771e49b64e834e9 

British Columbia Fire Locations (BC Wildfire Service)

This dataset includes wildfire location points in British Colombia, Canada for the current fire season. This includes both active and inactive fires. Data is updated every two hours. For more information, see:  https://catalogue.data.gov.bc.ca/dataset/2790e3f7-6395-4230-8545-04efb5a18800 

2023, 2022, 2021, 2020, 2019 Fire Perimeter History (NIFC)

These layers include wildfires whose discovery time falls within the given year. These are part of the ongoing project to represent a full history of wildfire perimeters. It is a different data source than the All-Time Fire Perimeter History described below. For more information, see:  https://data-nifc.opendata.arcgis.com/datasets/nifc::wfigs-wildland-fire-perimeters-full-history/about 

2000 – 2018 Fire Perimeter History

This data shows final wildfire perimeters from authoritative agency datasets. It displays wildfire incident data dating back to the year 2000. It was developed for use in the legacy GeoMAC application by USGS. For More information, see:  https://data-nifc.opendata.arcgis.com/datasets/nifc::historic-perimeters-combined-2000-2018-geomac/about 

Air Quality Readings and Air Quality Zones (AirNow)

AirNow is an offering from the US EPA in partnership with NOAA, NPS, NASA, and others that reports air quality using the official Air Quality Index (AQI), a color-coded representation of air quality over the last 24 hours. The point readings on the map are AirNow's most recently calculated air quality readings for that location, and the air quality zones are created via spatial interpolation of these readings.

Note that the Air Quality Index is calculated based on the last 24 hour period, so AirNow layers do not necessarily represent the current levels of PM 2.5  in the air- See the HRRR layer for current smoke levels. For more information on AirNow and AQI, see  https://www.airnow.gov/about-the-data/ 

Weather Warnings (Fire related, National Weather Service)

This layer shows NWS Weather Watches and Warnings, filtered for just wildfire related warnings. These include Red Flag Warnings, Extreme Fire Danger, Fire Warnings, and Fire Weather Watch types. For more information on these weather warnings and types, see:  https://www.weather.gov/lwx/warningsdefined 

Near Surface Smoke – Current and Forecast PM2.5 (NOAA HRRR)

The High-Resolution Rapid Refresh (HRRR) Smoke modeling system simulates the emission and transport of smoke from wildfires in the lower atmosphere in real time in high spatial resolution for the continental US. There is a layer for the 16hr (in the future) forecast, and a layer for the most current conditions.

The model uses data from HRRRX meteorological inputs, Rapid Refresh (RAP) with smoke experimental model, and polar-orbiting satellites VIIRS/Modis data. Map service provided by the  RealEarth group at SSEC/CIMSS University of Wisconsin – Madison . The data displayed in this layer is particulate matter smaller than 2.5 microns, PM 2.5  in micrograms (μg) per square meter (m 3 ). See the below legend graphic.

Other products in this map related to air quality, such as AirNow zones also provide PM 2.5  data in μg/m 3  . For more information, see:  https://rapidrefresh.noaa.gov/hrrr/HRRRsmoke/ 

WA Current Industrial Fire Precaution Levels (WADNR)

This layer shows the current industrial fire precaution levels (IFPL) by region in Washington. IFPL are an activity closure system to reduce wildfire risk. It applies to woods workers and other industrial forest users, including trailwork volunteers. For more information, see:  https://www.dnr.wa.gov/ifpl  

Imagery and Conditions (group)

Web Cams

This is actually a group layer containing webcams from a few different sources including California, Oregon, and Washington's respective departments of transportation, and California Office of Emergency Services. These points provide either contain the image within their popups, or contain links to the images that can be used to see the current conditions for wildfires, smoke, snow, etc. There are Fire Cameras, Traffic Cameras, and some other types.

Weather Stations (NOAA METAR)

These points represent weather stations and show various weather variables at each location. It is a live-feed dataset provided by ESRI from data supplied by NOAA on an hourly basis. More information on  METAR  data

NOHRSC Snow Analysis Data

This service contains layers for snow depth as well as snow water equivalent. Snow depth is the total depth of all snow on the ground, reported to the nearest whole inch. Snow Water Equivalent (SWE) is a commonly used measurement by hydrologists and water managers representing the amount of water that will be released from the snowpack when it melts. This also is in inches. The data is provided by the National Operational Hydrologic Remote Sensing Center (NOHRSC), a department within the National Weather Service (NWS). The data originates from satellite, airborne, and ground observations, and is modelled into the snow-depth dataset on an hourly basis with spatial resolution of about 1 square kilometer. For more information on the NOHRSC program, see  http://www.nohrsc.noaa.gov/technology/ 

Sentinel-2 Recent Satellite Imagery (Sentinel Hub)

The Sentinel-2 Imagery popup with the often hidden date field displayed

The Sentinel-2 Satellite Imagery is a near-real-time set of images of the world that are updated every few days. It's also fairly high-resolution making this imagery useful for planning around things like snow, wildfire smoke, or recently burned areas. The images come from the Copernicus Sentinel-2 Satellite mission of polar orbiting satellites, managed by the European Space Agency. The data is hosted by Sentinel Hub.

To view the date the image was taken - click or tap on the image, and a popup will appear with a table containing a complex code under id, and other fields to the side. Scroll right to reveal the date field in this table.

For more information on the Sentinel-2 Satellite mission, see  https://sentinel.esa.int/web/sentinel/missions/sentinel-2 

Sentinel-2 Backup Imagery

Occasionally, the above layer doesn't load properly. This ESRI-hosted version of the Sentinel imagery serves as a backup for when that occurs. It originates from the same data source, but it has slightly less sharp imagery that is more often late in delivery. This imagery does include the entire world, where the other layer only displays a rough buffer around the PCT. Also, note that sometimes the overview image (when you’re zoomed further out) will show images from the past. Zoom in further to see the most recent images.

GOES Real-Time Geocolor Imagery

This layer contains imagery that is not high-resolution, but is real time (it is updated every 10-15 minutes). GOES stands for Geostationary Operational Environmental Satellites. The satellites being "geostationary" means that they orbit in sync with the earth's rotation so that they always have the same view from space. This allows for continuous data coverage. This satellite mission is a collaborative effort between NOAA and NASA. For more information about the GOES program, see  https://www.goes-r.gov/mission/mission.html 

MODIS Satellite Imagery

This NASA-provided data contains imagery from the MODIS instrument on NASA’s Terra satellite. It is a natural looking image that is useful for viewing at regional scales. The data’s resolution is scaled to 250m per pixel at the equator. The data is updated continuously, but you will sometimes see black without imagery on your area of interest, that is because the satellite has not passed over that location yet today. You can view a map of the Satellite’s predicted passes at the following location:  https://www.ssec.wisc.edu/datacenter/polar_orbit_tracks/#satellite:TERRA;region:Global 

For more information about the Terra Satellite mission, see  https://www.nasa.gov/mission_pages/terra/index.html 

For more information about the MODIS instrument, see this  https://modis.gsfc.nasa.gov/about/ 

The Sentinel-2 Imagery popup with the often hidden date field displayed