Harrison, Lana D., Michael Backenheimer and James A. Inciardi (1995), Cannabis use in the United States: Implications for policy. In: Peter Cohen & Arjan Sas (Eds)(1996), Cannabisbeleid in Duitsland, Frankrijk en de Verenigde Staten. Amsterdam, Centrum voor Drugsonderzoek, Universiteit van Amsterdam. pp. 231-236.
© Copyright 1995, 1996 Centrum voor Drugsonderzoek, Universiteit van Amsterdam. All rights reserved.

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4  Marijuana supply, sales, and seizures

Lana D. Harrison, Michael Backenheimer and James A. Inciardi


According to the DEA, marijuana is not the same drug it was two decades ago. It has fallen heir to the technological revolution. In 1970, the average THC content of a marijuana plant was about 1.5%. Today this would be considered 'ditchweed' or inferior marijuana. Because of advanced technology including plant hormones and steroids, fertilizers, indoor hydroponic operations, and scientific horticulture practices, the potency of the cannabis plant has increased dramatically.

A sizable portion, but by no means all, domestic cultivation of cannabis involves sinsemilla. This is a Spanish word meaning 'without seeds'. In marijuana terminology it 'refers to the unfertilized flowering top of the female plant that contains the highest THC content' (DEA, no date, p. 2). It is this flowering or 'budding' that is cultivated by the sophisticated marijuana grower in an effort to extract the highest possible THC content from the plant. The growers have been extremely successful in this effort. A non-sinsemilla (pollinated) marijuana plant contains about 34% of leaf and bud components, the so-called usable materials. For a sinsemilla plant this figure increases to 58%. 'The average plant yield for mature, domestically grown sinsemilla is approximately 1.25 pounds per plant. The average plant yield for mature, domestically grown commercial grade marijuana is approximately three-quarters of one pound per plant' (Hsu, 1995).

According to the DEA, in 1989, the THC potency of sinsemilla was 6.95%. This rose to 10.15% in 1990 and climbed to 11.72% in 1991 before dropping to 8.34% in 1992. The potency (THC level) of marijuana plants, commercial grade but non-sinsemilla was 3.46% in 1989. For the next three years, 1990 through 1992, these percentages were 3.63, 3.13 and 3.68 respectively (DEA, 1993, p. 62). These figures serve to demonstrate the dramatic upsurge in marijuana potency over the last decade, particularly when it is borne in mind that the THC potency of the late 1970s and early 1980s averaged less than 2%. Not only does increased grower sophistication, but also the declining market share of imported marijuana - which tends of be lower quality - contribute to these trends in general THC content (DEA, 1993, p. 63).

A word of caution regarding the interpretation of potency is also in order. The primary data on marijuana potency in the United States comes from the National Institute on Drug Abuse's Marijuana Potency Monitoring Program located at the University of Mississippi. Measurements of potency are based on samples of marijuana obtained from DEA and state and local enforcement agencies. One caution is that the methodologies used in the 1970s to extract, measure and determine marijuana potency are 'primitive' in terms of methodologies and equipment currently available. Thus the issue of 'comparability' is most germane. Storage techniques prior to being sent to NIDA are also of concern. Any change or improvement in storage techniques might yield less degrading of samples than was true in the 1970s. Finally the issue of sampling rigor must be raised. The figures are based on a nonrandom sample of law enforcement seizures and reflects that average potency, not necessarily the potency of marijuana being smoked by Americans (see Hsu, 1995). While the cautions should in no way be thought of as reason for decreasing concern for the potency of marijuana, they should serve to plead the case for a more rigorous methodology involving the collection, sampling, storage and testing of marijuana (BJS, 1992, p. 54).


Prices of marijuana show wide variation by country of origin. Using wholesale prices per pound and mid-1991 prices, the price of marijuana of Mexican origin varied between $350 and $1600. For Colombian marijuana, this figure was $800 to $1,000 and for marijuana from Thailand, the price ranged from $2,000 to $3,000 per pound. Jamaican marijuana brought $1,500 to $2,000 per pound for commercial grade and $2,000-$3,000 for sinsemilla (BJS, 1992, p. 54). It is estimated that United States consumers of marijuana spent $9 billion in 1990 (BJS, 1992, p. 36).

The price of marijuana has been increasing on both a per pound and per ounce basis. During the early 1980s, a pound of commercial grade marijuana sold in the United States for between $350 and $600. Sinsemilla brought a higher price per pound, in the range of $1,000 to $2,000. In 1989 the price of a pound of commercial grade marijuana was between $350 and $2,000. An ounce of the same quality cost between $30 and $250. For sinsemilla, a pound cost between $700 and $3,000 and an ounce sold for between $100 and $300. A pound of commercial grade marijuana, in 1990, sold for between $250 and $3,000 and an ounce sold for between $25 and $300. For sinsemilla, the price ranges were $400 to $4100 for a pound and $80 to $350 for an ounce. The year 1991 saw commercial grade marijuana being sold for between $400 and $3,000 per pound and for between $40 and $550 per ounce. A pound of sinsemilla brought a price range of between $500 and $6,000 and an ounce brought a range of between $100 and $450. In the year 1992, a pound of commercial grade marijuana sold for between $300 and $3,000. An ounce of commercial grade brought between $40 and $450. The sinsemilla, in 1992, brought between $650 and $9,600 per pound and between $125 and $650 per ounce (BJS, 1992, p. 62). Figures on marijuana prices collected by the Community Epidemiology Work Group in June 1994 show essentially the same price structure (NIDA, 1994, p. 48). The range for a pound of sinsemilla in June, 1994 was between $650 and $9,000. For commercial grade marijuana, the range per pound was between $350 and $3,000.

According to a user survey conducted by Chalsma and Boyum (1994) for the ONDCP, the average price of marijuana in the United States was $55 for a quarter ounce. This amounts to about 8 dollars per gram which is very similar to the price charged for marijuana in Dutch coffeeshops.

To state the obvious, the cited prices demonstrate dramatic upsurge and offer tremendous potential for profit to the cultivator/trafficker of marijuana. Using indoor, high grade sinsemilla as an example, the DEA calculates the typical domestic marijuana grower to have approximately 250 plants per growing cycle. Using an estimate (which DEA purports as conservative) of one pound per plant and an average price of $3,000 per pound, the revenue generated would be of the magnitude of $750,000 per quarter (DEA, no date, p. 36).


The world production of marijuana is, indeed, 'Big Business.' In 1991 the Bureau of International Narcotics Matters at the U.S. Department of State estimated that 23,650 metric tons of marijuana were produced throughout the world (BJS, 1992, p. 36). Of course, not all of this production was consumed in the United States. Nevertheless, in economic terms, availability to a large extent translates into whether or not the supply of marijuana is sufficient to meet the demand and it would appear that world production is sufficient for the demand. As further evidence, the MTF Survey cited in the epidemiologic section of this report found that well over 80% of 17-18 year olds believed it was either 'fairly easy' or 'very easy' to obtain. Information from the DEA indicates that producers are doing everything in their power to meet the demand. Many growers, perhaps due to vigorous enforcement and aerial spraying of herbicide(s), moved their operation indoors. Sophisticated hydroponic operations do not require soil. The marijuana can, instead, be rooted in porous material such as lava rock or rockwool. Using state of the art delivery systems for water, fertilizers, carbon dioxide, and light, the indoor marijuana is superior to the outdoor product. Further, the indoor marijuana plant can come to maturity and be harvested within a four-month cycle; thus the potential for three harvests a year. In 1980, the DEA estimates that domestically grown marijuana was just 10% of the total. By 1992, perhaps due to successful intercept operations to stem the tide of marijuana imports and/or due to the ingenuity of marijuana growers to meet this shortfall, the 10% figure had grown to 25% with yield of approximately 4,500 to 5,300 metric tons (DEA, 1992, p. 1). Unsubstantiated but believable estimates of current domestic production indicate that more than 50% of the marijuana consumed in the United States is domestically cultivated. From these data then, it would appear that consumers of marijuana in the United States currently have little trouble obtaining it.

The table below provides Drug Enforcement Administration (DEA) estimates of domestic marijuana production for 1988 to 1992.

Table 7. DEA Estimates of Domestic Marijuana Production for 1988 to 1992 in Metric Tons.
1988 1989 1990 1991 1992
Total Production 4,350 - 4,850 5,000 - 6,000 5,000 - 6,000 3,615 - 4,615 2,595 - 3,095

However, Chalsma and Boyum (1994) estimate domestic marijuana production for the ONDCP using survey data on consumption at about 1000 metric tons, about 20% of which fails to reach the market. They estimated total marijuana consumption in 1992 at about 1600 metric tons, with half grown domestically and half imported. Clearly, DEA estimates of marijuana production are not consistent with the consumption-based estimates of Chalsma and Boyum. Further, the DEA estimates only about 25% of the marijuana consumed in the U.S. is grown domestically. Since we're discussing production of an illegal drug, we can't be sure which, if either, estimate is closer to the truth.

Because of its high potency, there is a ready market for export of U.S. grown marijuana, an issue that the government, as yet, appears to have given little attention. To meet the shortfall in domestic demand, a significant amount of marijuana is still imported into the United States. Colombia used to be the primary exporting country. However, due to the success of interdiction efforts and the huge profit and lower bulk of cocaine, Colombia no longer leads in exports. At this time, Mexico is chief among the countries making marijuana available in the United States. In 1990 it is estimated that Mexico cultivated 19,715 metric tons of marijuana (of a worldwide total of 25,600 metric tons). For 1991, worldwide cultivation of marijuana was dramatically reduced to 13,465 metric tons with Mexico accounting for 7,775 metric tons. The year 1992 saw worldwide cultivation of 13,058 metric tons of marijuana with Mexico producing 7,795 metric tons. In 1993, worldwide marijuana cultivation was 14,407 metric tons with Mexico's share being 6,280 metric tons (U.S. Dept. of State, 1994, p.5). The Mexican growers are using new technology to produce a grade of marijuana that can successfully compete with that domestically grown (DEA,1992, p. 1). Other countries smuggling marijuana into the United States include Colombia, Jamaica and Thailand (BJS, 1992, pp. 50-51).

Street supplies of marijuana are, in general, plentiful. An assessment of indicator data in major metropolitan areas throughout the United States in 1994 found evidence of widespread marijuana availability. Only in Detroit and Washington, D.C. were there indications (such as increasing prices) that demand was outstripping supply. The use of 'blunts' (marijuana inserted or rolled into a hollowed out cigar) was also reported in many metropolitan areas (NIDA, 1994, pp. 46-47).


Having addressed the issues of increased potency, easy availability and rising prices, it is important to look at the other side of this equation - the effectiveness of law enforcement authorities in reducing the supply of marijuana. One such measure would be the number of arrests associated with the eradication of marijuana sites. Here we are not speaking primarily of dealers and users but are rather addressing arrests associated with the domestic growing of marijuana.

From the period 1987 through 1990, efforts to eradicate marijuana were largely focused on outdoor cultivation of marijuana. In 1987 such efforts resulted in 6,502 arrests. This figure decreased in 1988 to 6,062 and further decreased to 5,76l in 1989 and 5,729 in 1990. In 1991, efforts turned from 'whack and stack' to placing emphasis on carefully planned, quality investigations and a realization that many marijuana growers had been driven indoors. The results, in 1991, were a 63% increase in arrests to 9,364. For 1992, arrests rose still higher to 12,369 (a 32% increase over 1991 and double the 1990 arrest figure) (DEA, 1992, p. 29). Of the 12,369 arrests in 1992, ten states accounted for 7,548 arrests or 61% of the total. Indiana and California with 1813 and 1551 arrests each led the states in this category (DEA, 1992, p. 13).

Eradication of marijuana crops is another measure of the effectiveness of supply reduction efforts. With respect to domestic production in 1992, it is estimated that 48.6 thousand outdoor plots were eradicated. This breaks out to 7.5 million cultivated outdoor plants. This figure, however, may include tended ditchweed, a low potency marijuana that grows wild and is usually mixed for sale with better grade marijuana. For the same year (1992), approximately 264.2 thousand ditchweed plants were eradicated. In addition, approximately 2.4 million outdoor sinsemilla plants were eradicated. Indoor growth of marijuana and sinsemilla, due to its high potency, was of special concern to enforcement authorities. The year 1992 saw 3,849 'indoor grows' eradicated. This amounted to 349.3 thousand plants (most of which can be assumed to be sinsemilla). Thus, in total some 272.0 million plants were eradicated (DEA, 1992, p.27).

Available figures for 1993 show somewhat unusual numbers. Some 64.1 thousand outdoor plots, approximately a 32% increase over 1992, were eradicated. This amounted to 4.0 million plants (may include ditchweed) but was still a dramatic downturn from the 7.5 million 1992 figure cited earlier. It would appear that the plots eradicated in 1993 were significantly smaller in size than those eradicated in 1992. In terms of indoor operations, in 1993, about 3,347 'indoor grows' were eradicated amounting to 290.0 thousand plants, a major downturn from the cited 1992 totals (Maguire and Pastore, 1994, p. 464).

Another estimate of drug seizures can be made by citing data from the Federal-wide Drug Seizure System (FDSS). These data represent the combined efforts of the DEA, the FBI, the U.S. Customs Service (within the jurisdiction of the United States) and maritime seizures by the U.S. Coast Guard. For Fiscal Year 1990, FDSS data show 500,310 pounds of marijuana/hashish as having been seized. For Fiscal Year 1991, this figure is 677,281 pounds. Fiscal Year 1992 saw this figure increase to 787,391 pounds. Preliminary estimates for Fiscal Year 1993 are 778,194 pounds (BJS, 1994, p. 5).


BUREAU OF JUSTICE STATISTICS,. 1992. Drugs, Crime and the Justice System. Washington, D.C.: U.S. Department of Justice, Office of Justice Programs, USGPO.

BUREAU OF JUSTICE STATISTICS. 1994. 'Fact Sheet: Drug Data Summary,' Drugs and Crime Data. Washington, D.C.: U.S. Department of Justice, Office of Justice Programs.

CHALSMA, ANDREW LOCKWOOD AND DAVID BOYUM. 1994. Marijuana Situation Assessment. Washington, DC: Office of National Drug Control Policy.

DRUG ENFORCEMENT ADMINISTRATION (DEA). no date. 'Domestic Marijuana Eradication: A Success Story.' Washington, D.C.: U.S. Department of Justice, DEA.

DEA. 1992. 1992 Domestic Cannabis Eradication/Suppression Program Washington, D.C.: U.S. Department of Justice.

DEA. 1993. U.S. Drug Threat Assessment. Washington, D.C.: U.S. Department of Justice, Intelligence Division.

HSU, MAGGIE. 1995. 'Is Marijuana Potency Increasing?' CESAR FAX Vol. 4:7 (February 20, 1995), College Park, MD: Center for Substance Abuse Research.

MAGUIRE, KATHLEEN AND ANN PASTORE (EDS.). 1994. Sourcebook of Criminal Justice Statistics -1993. Washington, D.C.: U.S. Department of Justice, Bureau of Justice Statistics, Washington, D.C.: USGPO.

NATIONAL INSTITUTE ON DRUG ABUSE. 1994. Epidemiologic Trends in Drug Abuse Volume I: Highlights and Executive Summary. Rockville, MD.: U.S. Department of Health and Human Services, NIDA.

U.S. DEPARTMENT OF STATE. 1994. 1994 International Narcotics Control Strategy Report as cited in Bureau of Justice Statistics, 'Fact Sheet: Drug Data Summary,' Drugs and Crime Data. Washington, D.C.: U.S. Department of Justice, Office of Justice Programs.

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