association between marijuana use and perception of great risk of harm and potential consequences to a person’s health and well-being.

Although marijuana is the most commonly used illicit drug in America, the percentages using marijuana and the attitudes regarding the risk of marijuana use are not the same across states or even within each state. Within each state, patterns of substance use and corresponding attitudes differ. Data on small geographic areas provide insight into marijuana use and attitudes about marijuana use that can help state and local public health authorities better understand and address any needs in their communities. The National Survey on Drug Use and Health (NSDUH) can help address the need for more localized information.

This issue of The CBHSQ Report uses combined 2012 to 2014 NSDUH data to present estimates of past month marijuana use and perceptions of great risk of harm from smoking marijuana once a month among people aged 12 or older in 362 substate regions, the 50 states, and the District of Columbia. In most states, the substate regions are defined in terms of single counties or groups of counties; in some states, the regions are defined entirely in terms of census tracts (in Connecticut, the District of Columbia, and Massachusetts), parishes (in Louisiana), boroughs/census areas (in Alaska), a combination of counties and census tracts (in California and Delaware), and a combination of counties and independent cities (in Maryland, Missouri, Nevada, and Virginia). The Substance Abuse and Mental Health Services Administration (SAMHSA) works with state substance abuse/mental health agency representatives to define substate areas that meet state needs and reporting requirements while ensuring that the NSDUH sample sizes were large enough to provide estimates with adequate precision. These substate-level estimates provide local-level information on behavioral health outcomes that states find useful for planning, reporting, and providing useful data for prevention and intervention efforts.⁹ The 2012 to 2014 estimates in this report are based on substate boundaries that reflect the current state needs and reporting requirements and may not be comparable with substate estimates from prior years.

Marijuana use estimates are displayed on a U.S. map (Figure 1). To produce the map, substate region estimates (shown to two decimal places in Table S1) were first ordered from lowest to highest percentage of past month marijuana use. The substate regions were then categorized into three approximately equal groups based on their percentage. Substate regions in the lowest third (i.e., with the lowest percentages) are indicated in blue (122 substate regions), the middle third are in white (119 substate regions), and the third with the highest percentages are in red (121 substate regions). To distinguish among the substate regions that display relatively higher percentages, the "highest" third in red was further subdivided into dark red for the 16 substate regions with the highest estimates, medium red for the 33 substate regions with the next highest estimates, and light red for the 72 substate regions in the third highest group. The "lowest" third was categorized in a similar way using three distinct shades of blue. Estimates of perceptions of risk of harm from using marijuana are displayed in Figure 2. On this map, the colors are reversed from those in Figure 1, so the highest estimates of perceived risk of harm from using marijuana are shown in blue and the lowest estimates are shown in red. Overall, the seven groups in each map were constructed to represent a distribution that is somewhat symmetric, like a normal distribution (in terms of the number of estimates assigned to each group). In some cases, a category could have more or fewer substate regions because two (or more) substate regions have the same estimate (to two decimal places). When such ties occurred at the "boundary" between two groups, all substate regions with the same estimate were assigned to the lower group. Individual state maps at https://www.samhsa.gov/data/ provide more granularity in areas too small to display clearly on the U.S. maps. Table S1 provides estimates associated with each map. Ninety-five percent confidence intervals are included as a measure of precision for each estimate.¹⁰ For state-specific maps that show the variations across substate areas within each state, see https://www.samhsa.gov/data/.

Findings in this report are annual averages based on combined 2012 to 2014 NSDUH data from approximately 204,000 respondents in the civilian noninstitutionalized population aged 12 or older. Estimates were derived from a complex statistical model in which substate data from NSDUH were combined with other local area data to enhance statistical power and analytic capability.¹¹

Nationally, an annual average of 20.3 million people aged 12 or older used marijuana in the past month based on combined 2012 to 2014 NSDUH data. This is equivalent to approximately 1 in 13 or 7.73 percent of people aged 12 or older using marijuana in the past month. Across census regions, estimates of past month marijuana use were 9.70 percent in the West, 8.36 percent in the Northeast, 7.28 percent in the Midwest, and 6.43 percent in the South (Table S1).¹² At the substate level, past month marijuana use ranged from 3.93 percent in a substate region in the southernmost part of Texas¹³ to 15.46 percent in San Francisco, California (Figure 1 and Table S1).

Of the 16 substate regions with the highest percentages of past month marijuana use, 8 were in the West (3 in Colorado; 2 in California; and 1 each in Alaska, Oregon, and Washington), 7 were in the Northeast (3 in Rhode Island, 2 in Vermont, and 1 each in Maine and Massachusetts), and 1 was in the South (District of Columbia). No substate areas in the Midwest were included in the category with the highest percentages of past month marijuana use.

Of the 17 substate regions that had the lowest percentages of marijuana use, 8 were in the South (2 each in Tennessee and Texas; and 1 each in Alabama, Louisiana, Oklahoma, and West Virginia), 5 were in the Midwest (2 each in Kansas and North Dakota and 1 in Iowa), 3 were in the West (all in Utah), and 1 was in the Northeast (Pennsylvania).

The combined 2012 to 2014 data indicate that an annual average of 74.9 million people aged 12 or older perceived great risk of harm from smoking marijuana once a month. This translates to about 2 out of every 7 people (28.50 percent) perceiving a great risk of harm from monthly marijuana use. Across census regions, perceptions of great risk of harm from smoking marijuana once a month were 32.60 percent in the South, 26.56 percent in the Northeast, 26.11 percent in the Midwest, and 25.64 percent in the West (Table S1). At the substate level, perceptions of great risk of harm from smoking marijuana once a month ranged from 14.15 percent in Ward 3 in the District of Columbia—in the western section of the District—to 49.29 percent in Florida’s combined Circuits 11 and 16, which include Miami-Dade and Monroe Counties in the southernmost part of the state (Figure 2).

Of the 16 substate regions that had the highest percentages of perception of great risk of harm from smoking marijuana once a month (i.e., regions with higher percentages of people aged 12 or older indicating that there was a great risk of harm from monthly marijuana use), all 16 were in the South (4 in Mississippi; 3 each in Alabama, Arkansas, and Texas; and 1 each in Florida, Kentucky, and Louisiana).

Of the 16 substate regions that had the lowest percentages of perception of great risk of harm from smoking marijuana once a month (i.e., regions with fewer percentages of people aged 12 or older indicating that there was a great risk of harm from monthly marijuana use), 10 were in the Northeast (5 in Maine, 3 in New Hampshire, and 1 each in Massachusetts and Rhode Island), 4 were in the South (all in the District of Columbia), 2 were in the West (1 each in Oregon and Washington).

Some substate regions within the same state and the District of Columbia have notable variations in the percentages of marijuana use and the perceptions of risk associated with marijuana use among people aged 12 or older. Notable variations can occur in large areas, such as California, and in small areas, such as the District of Columbia.

Figures 3 and 4 show substate estimates for California and the District of Columbia. As with the maps shown previously, the assignments of the substate areas in California and the District of Columbia were created by dividing 362 substate regions, nationally, into 7 groups based on the magnitude of their percentages. Figures 3 and 4 present close-up looks at the variations across substate regions for California and the District of Columbia that were previously shown in the national maps (Figures 1 and 2). The substate regions within California and the District of Columbia are labeled in Figures 3 and 4. For substate region definitions, see the "2012–2014 National Survey on Drug Use and Health Substate Region Definitions" at https://www.samhsa.gov/data/.

In California, past month marijuana use ranged from 6.18 percent in Los Angeles Service Planning Area (SPA) 3—in the San Gabriel Valley in the southeastern part of Los Angeles County—to 15.46 percent in San Francisco (Figure 3 Panel A] and Table S1).¹⁴ A high percentage of marijuana use also occurred in California’s Region 1R (13.97 percent), consisting of 15 counties in the northern section of the state. Lower percentages of marijuana use occurred mostly in areas in the central and southern sections of the state (Los Angeles SPA 3 [San Gabriel Valley] and SPA 7 [East], Region 17R, Region 18R [San Bernardino], Region 6 [Santa Clara], Regions 13 and 19R, Los Angeles SPA 2 [San Fernando Valley], Region 14 [Orange], and Region 15R [Fresno]) and ranged from 6.18 percent to 8.10 percent.

This report shows that the percentages of marijuana use and perceptions of the risk associated with marijuana use by substate region vary across the country and within each state and the District of Columbia. The maps and tables presented can help state policymakers and prevention specialists quickly see if prevention or education efforts are needed in their state and where. For example, the highest percentages of marijuana use occurred in substate areas in several northeastern and western states and in the District of Columbia. Most of the substate areas with the lowest percentages of perception of great risk of harm from smoking marijuana are in the District of Columbia, Maine, and New Hampshire.

As seen in Figures 1 and 2 and Table S1, there is a significant negative relationship between marijuana use and perceived great risk at the substate level across the United States. That is, substate regions with higher percentages of marijuana use were more likely to have lower percentages of the population who think there is great risk in using marijuana, whereas substate regions with lower percentages of marijuana use tend to have higher percentages of the population who think there is great risk in using marijuana. In fact, the correlation between the 362 substate estimates of past month marijuana use and the 362 substate estimates of perceived great risk of harm in using marijuana monthly is -0.72.

Across the United States, discourse continues over the public health implications of marijuana use in the general public, the media, the substance use research community, and among federal, state, and local policymakers. Marijuana use in the general population is an ongoing challenge for the nation as a whole and for the states individually. As states continue to examine their laws regarding marijuana use, monitoring national, regional, state, and substate estimates of marijuana use and attitudes toward use may also help state and local policymakers plan for and allocate resources to address marijuana use. For more information on addressing marijuana use, see https://www.samhsa.gov/capt/tools-learning-resources/youth-marijuana-risk-protective-factor-resources and https://www.drugabuse.gov/drugs-abuse/marijuana.

The combined 2012 to 2014 NSDUH estimates for marijuana use and perceptions of risk of harm from marijuana use are available, along with 23 additional behavioral health measures for 384 substate areas, 25 aggregate substate areas, 50 states and the District of Columbia, 4 census regions, and the United States. The methodology that generated these estimates is available online at https://www.samhsa.gov/data/. Of the combined 384 substate areas and 25 aggregate substate areas, 362 of these are shown in the maps (mostly substate areas, but for some states, the areas shown in the maps are aggregate substate areas). This report discusses two of the estimates for the 362 substate areas displayed in the maps.

The 23 additional estimates include measures of substance use and mental health issues, including use of illicit drugs (e.g., marijuana use, cocaine use, nonmedical use of prescription pain relievers), alcohol, and tobacco; substance use disorders; needing but not receiving treatment for a substance use problem; serious mental illness; depression; and suicidal thoughts. Also provided are national maps for all measures and detailed tables including percentages for each substate region, state, census region, and the nation for people aged 12 or older; detailed tables by age group; and state-specific tables and maps. The state maps are particularly useful in areas too small to display clearly on the U.S. maps.

1. Center for Behavioral Health Statistics and Quality. (2015). Behavioral health trends in the United States: Results from the 2014 National Survey on Drug Use and Health (HHS Publication No. SMA 15-4927, NSDUH Series H-50). Retrieved from https://www.samhsa.gov/data/sites/default/files/NSDUH-FRR1-2014/NSDUH-FRR1-2014.pdf
2. Center for Behavioral Health Statistics and Quality. (2015). Risk and protective factors and initiation of substance use: Results from the 2014 National Survey on Drug Use and Health. Retrieved from https://www.samhsa.gov/data/sites/default/files/NSDUH-DR-FRR4-2014rev/NSDUH-DR-FRR4-2014.pdf
3. White House, Office of National Drug Control Policy. (n.d.). Answers to frequently asked questions about marijuana: Isn't marijuana generally harmless? Retrieved from https://www.whitehouse.gov/ondcp/frequently-asked-questions-and-facts-about-marijuana
4. Anthony, J. C., Warner, L. A., & Kessler, R. C. (1994). Comparative epidemiology of dependence on tobacco, alcohol, controlled substances, and inhalants: Basic findings from the National Comorbidity Survey. Experimental and Clinical Psychopharmacology, 2(3), 244–268. doi:10.1037/1064-1297.2.3.244. Retrieved from http://www.umbrellasociety.ca/web/files/u1/Comp_epidemiology_addiction.pdf
5. Center for Behavioral Health Statistics and Quality. (2013, February). The DAWN Report: Highlights of the 2011 Drug Abuse Warning Network (DAWN) findings on drug-related emergency department visits. Rockville, MD. Retrieved from https://www.samhsa.gov/data/2k13/DAWN127/sr127-DAWN-highlights.pdf
6. Center for Behavioral Health Statistics and Quality. (2015). Receipt of services for behavioral health problems: Results from the 2014 National Survey on Drug Use and Health. Retrieved from https://www.samhsa.gov/data/sites/default/files/NSDUH-DR-FRR3-2014/NSDUH-DR-FRR3-2014/NSDUH-DR-FRR3-2014.pdf
7. Okaneku, J., Vearrier, D., McKeever, R. G., LaSala, G. S., & Greenberg, M. I. (2015). Change in perceived risk associated with marijuana use in the United States from 2002 to 2012. Clinical Toxicology, 53(3), 151–155. doi:10.3109/15563650.2015.1004581
8. Research on the inverse relationship between perceptions of harm and use has focused on adolescents. For more information, see Miech, R. A., Johnston, L. D., O'Malley, P. M., Bachman, J. G., & Schulenberg, J. E. (2015). Monitoring the Future national survey results on drug use, 1975–2014: Volume I, secondary school students. Ann Arbor, MI: Institute for Social Research, University of Michigan. The results of this study may not generalize to the population of people aged 12 or older.
9. Substance use and mental health officials from each of the 50 states and the District of Columbia typically define these substate areas to correspond to areas reported in their applications for the Substance Abuse Prevention and Treatment Block Grant (SABG) administered by SAMHSA. The SABG program provides financial and technical assistance to the 50 states, the District of Columbia, and other jurisdictions to support substance abuse prevention and treatment programs and to promote public health. States use NSDUH substate estimates for a variety of purposes, including strategic planning and program development, production of epidemiological profiles for briefing state legislatures and informing the public, allocation of funds to areas based on the need for services, and other uses.
10. In this report, substate estimates are discussed in terms of their observed rankings because they provide useful context. However, a substate region having a highest or lowest estimate does not imply that the substate region's estimate is significantly higher or lower than the estimate of the next highest or lowest substate region. Similarly, the seven categories were not selected to represent statistical differences across categories or to correspond to proximity to a target public health threshold for a particular measure. For example, the division of substate regions into seven categories does not indicate that substate regions in the same category are statistically similar to each other. Furthermore, the size of the intervals (i.e., the difference between the upper and lower limits of each category) that define the map boundaries is not necessarily uniform across each category. When comparing two substate region percentages, the method of overlapping confidence intervals is more conservative (i.e., it rejects the null hypothesis of no difference less often) than the standard method based on Z statistics when the null hypothesis is true. Even if confidence intervals for two substate regions overlap, the two estimates may be declared significantly different by the test based on Z statistics. Hence, the method of overlapping confidence intervals is not recommended to test the difference of two substate region estimates. A detailed description of the method of overlapping confidence intervals and its comparison with the standard methods for testing of a hypothesis is given in the following articles: (a) Schenker, N., & Gentleman, J. F. (2001). On judging the significance of differences by examining the overlap between confidence intervals. American Statistician, 55(3), 182–186. (b) Payton, M. E., Greenstone, M. H., & Schenker, N. (2003). Overlapping confidence intervals or standard error intervals: What do they mean in terms of statistical significance? Journal of Insect Science, 3, 34.
11. Estimates presented in this report are derived from a hierarchical Bayes model-based small area estimation procedure in which NSDUH data at the substate level are combined with local area county and census block group/tract-level data from the area to provide more precise estimates of substance use and mental health outcomes. With 3 years of combined NSDUH data, the sample sizes in the 362 substate regions ranged from 100 people to approximately 3,500 people.
12. The West has 13 states: AK, AZ, CA, CO, HI, ID, MT, NM, NV, OR, UT, WA, and WY. The South has 16 states plus the District of Columbia: AL, AR, DE, FL, GA, KY, LA, MD, MS, NC, OK, SC, TN, TX, VA, and WV. The Northeast has 9 states: CT, MA, ME, NH, NJ, NY, PA, RI, and VT. The Midwest has 12 states: IA, IL, IN, KS, MI, MN, MO, ND, NE, OH, SD, and WI.
13. This substate region is named Region 11 by the Texas Department of State Health Services and consists of the following 19 counties in the southernmost part of Texas: Aransas, Bee, Brooks, Cameron, Duval, Hidalgo, Jim Hogg, Jim Wells, Kenedy, Kleberg, Live Oak, McMullen, Nueces, Refugio, San Patricio, Starr, Webb, Willacy, and Zapata.
14. More information about SPAs in Los Angeles County can be found at http://publichealth.lacounty.gov/chs/SPAMain/ServicePlanningAreas.htm.

Hughes, A., Lipari, R.N., and Williams, M.R. Marijuana use and perceived risk of harm from marijuana use varies within and across states. The CBHSQ Report: July 21, 2016. Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration, Rockville, MD.