Online Sales of Marijuana: An Unrecognized Public
Theodore L. Caputi, BS,
Eric C. Leas, PhD, MPH,
Mark Dredze, PhD,
John W. Ayers, PhD, MA
The Internet hosts many unregulated marketplaces
for otherwise regulated products.
If extended to
marijuana (or cannabis),
online markets can
undermine both the U.S. Controlled Substances Act,
which bans marijuana sales, and the regulatory regimes
of states that have legalized marijuana. Consequently,
regardless of the regulatory regime, understanding the
online marijuana market should be a public health
priority. Herein, the scale and growth trajectory of the
online marijuana marketplace was assessed for the ﬁrst
time by analyzing aggregate Internet searches and the
links searchers typically ﬁnd.
First, the fraction of U.S. Google searches including the terms
marijuana,weed,pot,orcannabis relative to all searches was
described monthly from January 2005 through June 2017 using
data obtained from Google. Searches were also geotagged by state
(omitting Alaska, Montana, North Dakota, South Dakota, Ver-
mont, West Virginia, and Wyoming because of data access
restrictions). The subset of shopping searches was then moni-
tored by tracking queries that also included buy,shop,andorder
(e.g., buy marijuana) in aggregate. Searches that included killer,
cooking,orclay (e.g., weed killer) were considered unrelated and
excluded from all analyses.
Linear regressions were used to compute pooled means to
compare between time periods and log-linear regressions were
used to compute average growth. Raw search volumes were
estimated based on total Google search volume using comScore
Searches in a Google Chrome browser without cached data were
executed during July 2017 using the 12 combinations of marijuana
and shopping root terms (i.e., buy marijuana). The results would
be indicative of a Google user’s typical search results. The ﬁrst two
pages of links, including duplicates (N¼279, with seven to 12 links
per page), were analyzed (because nearly all searchers click a link
on the ﬁrst two pages, with as much as 42% selecting the ﬁrst
). Investigators recorded whether each linked site advertised
mail-order marijuana (excluding local deliveries in legal marijuana
states) and its order in the search results. Two authors agreed on all
labels. Analyses were computed using R, version 3.4.1.
Marijuana searches grew 98% (95% CI¼84%, 113%) as a
proportion of all searches from 2005 through the partial
2017 year (Figure 1). The subset of marijuana searches
indicative of shopping grew more rapidly over the same
period (199%, 95% CI¼165%, 243%), with 1.4–2.4
million marijuana shopping searches during June 2017.
Marijuana shopping searches were highest in Wash-
ington, Oregon, Colorado, and Nevada. The compound-
ing annual growth rate for marijuana shopping searches
since 2005 was signiﬁcantly positive (po0.05) in 42 of
the 44 studied locations (all but Alabama and Missis-
sippi), suggesting demand is growing across the nation.
Forty-one percent (95% CI¼35%, 47%) of shopping
search results linked to retailers promising mail-order
marijuana (Table 1). Retailers occupied 50% (95%
CI¼42%, 59%) of the ﬁrst page results and for eight
(of 12) searches, the ﬁrst link led to a mail-order marijuana
retailer. For some searches (e.g., order marijuana), all of the
ﬁrst-page links were marijuana retailers.
Millions of Americans search for marijuana online, and
websites where marijuana can be purchased are often the
top search result.
If only a fraction of the millions of searches and thousands
of retailers are legitimate, this online marketplace poses a
number of potential public health consequences.
could purchase marijuana online. Marijuana could be sold in
states that do not currently allow it. Initiation and marijuana
Department of Epidemiology and Public Health, University
College Cork, Cork, Republic of Ireland;
Wharton School, University of
Pennsylvania, Philadelphia, Pennsylvania;
Stanford Prevention Research
Center, Stanford University, Palo Alto, California;
Johns Hopkins University, Baltimore, Maryland; and
Graduate School of
Public Health, San Diego State University, San Diego, California
Address correspondence to: John W. Ayers, PhD, MA, Graduate School
of Public Health, San Diego State University, 2967 Four Corners Street,
Chula Vista CA 91914. E-mail: email@example.com.
&2018 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights
Am J Prev Med 2018;](]):]]]–]]] 1
dependence could increase.
Products may have inconsis-
tent potency or be contaminated. State and local tax revenue
(which can fund public health programs) could be negatively
Regulations governing online marijuana markets (even
if policy changes favor legalized marijuana) need to be
developed and enforced. Policing online regulations will
require careful coordination across jurisdictions at the
local, state, and federal level with agreements on how to
implement regulations where enforcement regimes con-
ﬂict. Online sales are already prohibited under virtually
every regulatory regime—all sales are illegal under federal
statute and legal marijuana states like Colorado
online sales—yet the market appears to be thriving.
Government agencies might work with Internet pro-
viders to purge illicit marijuana retailers from search
engines, similar to how Facebook removes drug-related
Moreover, online payment facilitators could
refuse to support marijuana-related online transactions.
This study was limited in that who is buying/selling
and the quantity of marijuana exchanged cannot be
measured. Further, some searches may be unrelated to
seeking marijuana retailers, and some retailers may be
illegitimate, including scams or law enforcement bait.
The volume of searches and placement of marijuana
retailers in search results is a deﬁnitive call for public
health leaders to address the previously unrecognized
dilemma of online marijuana.
This work was supported by a grant from the National Institutes of
Mental Health (R21MH103603). Mr. Caputi acknowledges scholar-
ships from the Joseph Wharton Scholars and the George J. Mitchell
Scholarship programs. Dr. Leas acknowledges a training grant from
the National Heart, Lung, and Blood Institute (T32HL007034). No
other ﬁnancial disclosures were reported by the authors of this
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2005 2008 2011 2014 2017
All marijuana searches
(per 10 million)
2005 2008 2011 2014 2017
Shopping / all marijuana
Average monthly marijuana shopping
searches (per 10 million) since 2016
Yearly increase in marijuana shopping
searches (per 10 million) since 2005
Figure 1. Internet searches for marijuana.
Note: “All Marijuana”searches are deﬁned as searches including one or
more of the following terms: marijuana,pot,cannabis, and/or weed.
“Marijuana Shopping”searches are deﬁned as searches including both
one of the marijuana terms and one of the following shopping searches:
shop,order, and/or buy after omitting ambiguous searches. Panel A
shows All Marijuana searches nationally, as a fraction per 10 million
total Google searches (query fraction). Panel B shows the ratio of
marijuana shopping searches to all marijuana searches nationally.
Panel C shows the average query fraction of Marijuana Shopping
searches between January 2016 and June 2017 by state. Panel D
shows the average annual increase in Marijuana Shopping searches
since 2005, computed through a log-linear least squares regression
model, where less than zero implies a declining trend.
Table 1. Online Mail-Order Marijuana Retailers on Internet
Search Engines, 2017
Yes 8 (67) 66 (50) 48 (32) 114 (41)
No 4 (33) 65 (50) 100 (68) 165 (59)
Note: Data were collected by executing searches in July 2017. Cells
show the frequency and percent of links (by column) in the ﬁrst two
pages of Google search results that claim to sell mail-order marijuana in
response to 12 searches that contained unique combinations of the
following terms: cannabis,marijuana,pot,orweed with buy,order,or
shop, such as buy cannabis,buy marijuana,buy pot,orbuy weed.
Searches were executed on a new Google browser without cached data.
Two authors agreed on the labels 100% of the time.
Caputi et al / Am J Prev Med 2018;](]):]]]–]]]2
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