Understanding extended day use of corridor trails

By Peter Pettengill

The growing use of backcountry trails at Grand Canyon National Park, Arizona, is a concern among trail users and managers alike (fig. 1). Observations by NPS staff and public comments on the park’s 2011 scoping process for the park’s backcountry management plan revision reveal this trend. Increasing use of corridor trails has led to user conflict, increased litter, abandoned gear, improper disposal of human waste, crowding at restrooms and attraction sites, an overburdened wastewater treatment plant, vehicle congestion and crowding at trailheads, and general concerns over trail courtesy among visitors. Furthermore, park rangers have reported increases in unprepared and injured rim-to-rim hikers and runners resulting in additional search-and-rescue responses. Increases in use levels and commensurate impacts are exacerbated by publicity through social and other popular media outlets. Hiking and running rim to rim, particularly, has been reported on by a number of popular magazines and numerous Facebook sites, which promote the traverse as a day trip.

Figure 1. Use of the three main trails of the Grand Canyon corridor is on the rise with an increase in endurance day hiking and trail running and consequences for the visitor experience.

NPS/Peter Pettengill

Grand Canyon’s 1988 Backcountry Management Plan provides guiding policy for corridor and other trails in the park’s more remote reaches (NPS 1988; see also the map). For example, overnight use limits for backpacking were established by the plan. Furthermore, it clearly notes that the number of daytime contacts a backcountry user has with other people is an important indicator of quality for visitor experience. While limits for overnight parties were implemented by the 1988 plan, day-use levels were not explicitly addressed. Still, use levels in the corridor have remained an issue in recent decades. Grand Canyon’s 1995 General Management Plan noted overcrowding on corridor trails as a planning issue (NPS 1995) and the park’s 2010 Foundation Statement referred to the 1988 Backcountry Management Plan as outdated and in need of review (NPS 2010).

Given that decades of research reveal that solitude is an important motivation among visitors to Grand Canyon’s backcountry (Towler 1977; Underhill et al. 1986; Stewart 1997; Backlund et al. 2006), and that the park’s 1988 backcountry management plan emphasizes limited daytime contacts among backcountry users as integral to the visitor experience, in 2013 park planners chose to reassess use levels and related visitor perceptions along corridor trails.

The study

This study was designed by park staff to address three questions. First, it would estimate what use levels along corridor trails actually are. Second, it would consider visitor perceptions of what use levels along corridor trails should be. Third, it would focus on a further understanding of issues along corridor trails and visitor perceptions of management interventions that could be used to address them.

We concentrated on inner canyon trail segments of the Bright Angel and South and North Kaibab Trails. Specifically, we studied the Bright Angel Trail from Indian Garden to Silver Bridge; the South Kaibab Trail from Tipoff to Black Bridge; and the North Kaibab Trail from Manzanita Rest Area to Clear Creek Junction (see map). Each of these trail segments begins approximately 5 miles (8 km) into the canyon and ends outside of Phantom Ranch. We chose inner canyon trail segments based on a reasonable expectation for relative solitude given distance from trailheads, and excluded the Phantom Ranch area based on its design as a place for people to gather, relax, and spend time.


We applied two separate methods to estimate use levels along corridor trails. The first employed automated visitor counters to approximate trail use volumes. Counters were established approximately 5 miles (8 km) into the canyon along each trail to coincide with the study area. Each counter consisted of an infrared sensor linked to a small memory unit that stored count data. The unit registered a count each time the sensor detected an infrared signature of a warm moving object. Count data were collected from 9 May to 5 July 2013.

The second approach involved park staff and volunteers collecting descriptive data regarding use levels along inner canyon trail segments. Staff and volunteers systematically counted the number of people they encountered while walking along inner canyon trail segments. They used hand counters and monitoring forms to record their observations. This form included such attributes as the date, start and end times of their hike, and the trail segment and direction hiked (fig. 2). Given limited resources for the study, we employed an opportunistic sampling plan in which staff and volunteers participated as their duties and free time allowed. While some bias may be acknowledged here, it was important to park researchers that sampling not be encouraged during the heat of the day. Exposure to extreme heat is a safety issue, and we thought that trail users would have also been less active during these time periods anyway. Monitoring forms were made available beginning 15 April and collected on 1 June 2013. An additional 16 forms were collected on this trail segment in spring 2014, and 14 more in fall of the same year. (The final study report at https://www.nps.gov/grca/learn/management/upload/Grand-Canyons-Corridor-Trails-Report
details all data collection along all trail segments.)

Figure 2. The study involved a questionnaire to be completed by a member of a trail user group and a monitoring form, shown here, to be filled out by park staff and volunteers.

We also designed an evaluative visitor survey to measure perceptions of what use levels along these trails should be and what management interventions should be used to address them. Approval to administer the survey was received in advance from the Office of Management and Budget. We administered the normative survey to a representative sample of hikers at Manzanita Rest Area along the North Kaibab Trail, at Indian Garden along the Bright Angel Trail, and at Phantom Ranch along the South Kaibab Trail (see map). Surveys were administered on weekdays and weekends between 27 April and 27 May 2013. We chose sampling locations strategically in order to facilitate sampling visitors shortly after they had traveled a segment of inner canyon trails.

At the start of each sampling day, surveyors stationed at each sampling location approached the first visitor group to arrive and asked a member of their group if he or she would be willing to participate in the survey. Visitors who agreed were given the survey instrument and provided verbal instructions about how to complete the questionnaire. Those who were unwilling or unable to participate were thanked for their consideration. After finishing a contact with a visitor group, the surveyor completed an entry on a survey response log and then asked the next visitor group to participate. This process continued throughout each sampling day. Of 573 people asked to participate in the study, 477 agreed. The overall response rate for the survey was 83%. We note that a full report of this research includes more comprehensive information on methods and results (Pettengill 2015) and that these sections have been condensed here for the purpose of this article.


Total daily use was variable over the course of the study period, as estimated from data recorded by the automated counters (fig. 3). Use peaked on 18 May, the first Saturday after the North Rim opened for the season, and was highest during weekends in the month of May. Overall, use began to taper off after Memorial Day weekend and during the warmer months of June and July. Though the counter does not discern among user types or specify the exact number of people on inner canyon trails each day, it does provide general estimates of total use along corridor trails and valuable information regarding overall use patterns and trends. The automated counter data are corroborated by visitor encounter surveys that also revealed more visitors on weekend days (Friday through Sunday) than on weekdays (Monday through Thursday; table 1). All counts are for all trail users, including day hikers, trail runners, backpackers, Phantom Ranch guests, mule trips, river exchanges, and administrative staff.

Figure 3. Visitor use counts from automated counters along the inner corridor trail system at Grand Canyon National Park, 9 May to 5 July 2013. (Data are available in the linked table.)

Table 1. Encounters among users of the South Kaibab Trail between Tipoff and Black Bridge, 15 April to 1 June 2013 (n = 44)

Minimum Maximum Average Observations
Monday to Thursday Friday to Sunday >45 <15
0 143 12 38 7 24

Results from the survey highlight visitor assessments of potential problems along corridor trails, including encounters among visitors, attitudes toward access, and perceptions of a range of possible management interventions aimed at preserving high-quality visitor experiences. For example, respondents were asked whether or not there were “too many other visitors” on inner canyon trail segments, if other visitors were “rude and inconsiderate,” and if there were “unacceptable impacts to park resources.” They were also asked to rate how much of a problem each of these was on a scale ranging from “not a problem” to a “big problem.” Results are summarized in table 2 and reveal that more than half of respondents did not think that any of these issues was a problem. However, 38% of visitors, the most for any issue, identified that “Too many other visitors” is either a small or big problem.

Table 2. Degree of problems along inner canyon trail segments as evaluated by survey respondents (n = 448)

Type of Problem Not a Problem Small Problem Big Problem Don’t Know
Too many other visitors 55% 35% 3% 6%
Rude and inconsiderate visitors 65% 18% 12% 5%
Unacceptable impacts to park resource 57% 23% 13% 7%

In order to evaluate the number of trail encounters among visitors and how this relates to perceptions of crowding we relied on two components of the questionnaire. First we asked respondents to rate how acceptable a range of descriptive simulated crowding scenarios would be if these conditions were experienced while hiking inner canyon trails. Each scenario described different numbers of visitors encountered, and respondents rated the acceptability of each on a scale ranging from 3 (very acceptable) to −3 (very unacceptable). We calculated average acceptability ratings for each scenario and plotted them on a social norm curve. As illustrated in figure 4, conditions along the South Kaibab Trail become unacceptable as hikers encounter approximately 45 or more other visitors between Tipoff and Black Bridge. Moreover, visitors prefer to experience around 15 such encounters.

Figure 4. Acceptability of trail user encounter rates along South Kaibab Trail between Tipoff and Black Bridge as measured by surveys administered at end of South Kaibab Trail segment from 27 April to 27 May 2013. The point at which the curve crosses the zero line denotes the point at which conditions become unacceptable and indicates the trade-off between use levels and acceptability.

The second evaluative component related to crowding involved asking respondents to “estimate the number of other visitors you saw” between Tipoff and Phantom Ranch. Approximately 25% of respondents reported observing fewer than 15 other visitors while around 28% reported seeing 46 or more; 12% reported not being able to remember (table 3).

Table 3. Number of visitors seen by survey respondents between Tipoff and Phantom Ranch along the South Kaibab Trail (n = 135)

Number of Visitors Reported Seen by Percentage
0–15 16–30 31–45 46–60 61–100 >100 Can’t remember
26% 27% 7% 12% 12% 4% 12%
Note: Not all survey respondents traveled along the South Kaibab Trail during their trip.

We asked a battery of questions regarding visitor attitudes toward backcountry management priorities, particularly backcountry access. On a scale ranging from “strongly agree” to “strongly disagree,” respondents recorded their feelings related to the following statements: “If people feel crowded, access should be reduced,” “If visitor-caused resource impacts are high, access should be reduced,” “If solitude is lost, access should be reduced,” and “Access should never be reduced, even if use is high.” Results are synthesized in table 4. Responses related to crowding and solitude lacked agreement. Whereas visitor-caused impacts had the highest level of agreement (73% agreed or strongly agreed), 61% of respondents disagreed or strongly disagreed with the statement that “access should never be reduced, even if use is high.”

Table 4. Survey respondents’ level of agreement with access-related statements

Statements n Strongly Agree Agree Neutral Disagree Strongly Disagree Don’t Know
If people feel crowded, access should be reduced 448 9% 28% 27% 24% 10% 2%
If visitor-caused resource impacts are high, access should be reduced 441 25% 48% 15% 6% 4% 1%
If solitude is lost, access should be reduced 437 7% 25% 31% 25% 11% 1%
Access should never be reduced, even if use is high 438 6% 11% 20% 39% 22% 1%

Another series of questions measured the level of visitor support for various backcountry management options. Respondents indicated on a scale ranging from “strongly support” to “strongly oppose” the extent to which they support “more education regarding trail etiquette/appropriate behavior,” limiting “group sizes for day use to 11 people or less,” and requiring “permits … for day use (limits and no fees).” Results from these questions are synthesized in table 5. The group size limit intervention lacked general support or opposition. Education intervention had the highest level of support at 76% (“support” or “strongly support”), while permit intervention had the most opposition with 55% “opposed” or “strongly opposed.”

Table 5. Extent of support of survey respondents for a range of possible management interventions

Management Intervention n Strongly Support Support Neither Oppose Strongly Oppose Don’t Know
More education regarding trail etiquette/appropriate behavior 451 34% 42% 19% 3% 1% 1%
Limit group sizes for day use to 11 people or less 447 10% 26% 23% 21% 16% 4%
Permits required for day use (limits and no fees) 444 4% 19% 19% 31% 24% 3%


This study developed an increased understanding of issues related to backcountry trail management at Grand Canyon. For example, each component of the study contributed to a greater understanding of the scope of problems related to use levels and crowding. Results from the evaluative survey reveal increasing trail use levels may become unacceptable to visitors. In the case of the South Kaibab Trail, encounters of more than approximately 45 visitors per individual between Tipoff and Black Bridge help define this threshold. Results from descriptive encounter rate data reveal that visitors can, and do, experience unacceptable conditions while traveling along backcountry trails and that the extent of this issue can be considerable. The maximum number of encounters observed was 143 over the course of approximately one hour; however, the frequency with which thresholds are exceeded is relatively limited. For example, 45 or more visitors were encountered along the South Kaibab Trail only 16% of the time. Furthermore, preferred conditions (15 or fewer encounters) were observed approximately 57% of the time. Unacceptable conditions tended to occur more on weekends than weekdays during the study period, and this likelihood is corroborated by results from automated counters.

In addition to expanding understanding of visitor use, this study shed light on visitor perceptions of potential management interventions. For example, it is clear that visitors more strongly support indirect management interventions than direct actions. The strong level of support for more education regarding trail etiquette and appropriate behavior led park staff to develop an electronic media and sign campaign called “Trail Courtesy Practices That Leave No Trace” in 2014.[1] These practices were described in partnership with the Leave No Trace Center for Outdoor Ethics, and have been incorporated into outreach that includes both traditional and electronic media. Signs describing trail courtesy practices, for example, have been posted at trailheads and on park shuttle buses. A park website was developed to disseminate the information, and social media, including Grand Canyon’s Facebook page and Twitter feed, have allowed park staff to emphasize educational messages electronically during the busiest times of year (fig. 5). Direct management interventions, including group size limits, day-use permits, and limiting access, clearly received less support from visitors. However, these tactics would likely be the most effective in maintaining acceptable social conditions along park trails. Further consideration of direct management actions may necessitate greater public input through the formalized National Environmental Policy Act (NEPA) process.

Figure 5. Example of an educational message distributed seasonally through social media and on the park’s trail courtesy practices website (https://www.nps.gov/grca/planyourvisit/courtesy.htm).

NPS/Victoria Allen and Michael Quinn


Visitor use studies provide park managers with an opportunity to further understand issues related to park resources and visitor experience. The benefits from this study involve being able to compare actual conditions, visitor perceptions of those conditions, and visitor perceptions of management options for selected segments of the popular corridor trail system at Grand Canyon National Park. However, the real strength of visitor use studies remains in continued research and monitoring. For instance, will the extent and frequency of high-use periods increase over time? Will park visitors experience unacceptable conditions along backcountry trails more often in the future? Will public support for limiting access change? The answers to these questions will help park managers protect park resources and provide for enjoyable visitor experiences, but they will not be possible without an ongoing program of visitor use research.

Each of the articles in this “In Focus” section demonstrates how research may help inform broader discussions of management reform and lead to greater awareness and education through public outreach. Furthermore, the frameworks and methods described suggest a means for monitoring impacts on park resources and visitor experience in the future. As noted in the introduction to this set of articles, recreational use of the corridor has changed over time and park officials are now reviewing comments on a draft environmental impact statement to help adapt to this change. Ultimately, sound management judgment by park officials will be needed to directly prescribe policy. A final decision regarding the draft environmental impact statement is expected in the next year.


Backlund, E., W. Stewart, and Z. Schwartz. 2006. Backcountry day hikers at Grand Canyon National Park. Technical Report. On file at Grand Canyon National Park. University of Illinois, Champaign, Illinois, USA. Available at https://www.nps.gov/grca/learn/management/upload/Backcountry_Day_Hikers_Final_Report.pdf.

National Park Service (NPS). 1988. Backcountry Management Plan. National Park Service, Grand Canyon National Park, Arizona, USA. Available at https://www.nps.gov/grca/learn/management/upload/1988_BCMP.pdf.

———. 1995. General Management Plan. National Park Service, Grand Canyon National Park, Arizona, USA. Available at https://www.nps.gov/grca/learn/management/upload/GRCA_General_Management_Plan.pdf.

———. 2010. Foundation Statement. National Park Service, Grand Canyon National Park, Arizona, USA. Available at https://www.nps.gov/grca/learn/management/upload/grca-foundation20100414.pdf.

Pettengill, P. 2015. Grand Canyon’s corridor trails: A study of visitor use and experience. Report. National Park Service, Grand Canyon National Park, Arizona, USA. Available at https://www.nps.gov/grca/learn/management/upload/Grand-Canyons-Corridor-Trails-Report-July2016.pdf.

Stewart, W. 1997. Grand Canyon overnight backcountry visitor study: Use of diary-like techniques. Report submitted to Grand Canyon National Park through cooperative agreement INT-92733-RJVA. Grand Canyon National Park, Grand Canyon, Arizona, USA.

Towler, W. L. 1977. Hiker perception of wilderness: A study of social carrying capacity of Grand Canyon. Thesis. University of Arizona, Tucson, Arizona, USA.

Underhill, H., W. Stewart, R. Manning, and E. Carpenter. 1986. A sociological study of backcountry users at Grand Canyon National Park. Technical Report 17. National Park Service, Cooperative Parks Studies Unit, University of Arizona, Tucson, Arizona, USA.

About the author

Peter Pettengill is an assistant professor of environmental studies at St. Lawrence University, Canton, New York. He formerly worked as an outdoor recreation planner at Grand Canyon National Park, Arizona. He can be reached by e-mail at ppettengill@stlawu.edu.