Interesting read (if you read spanish) "La prehistoria de la marihuana en Colombia"

-- "The prehistory of marijuana in Columbia"

Eduardo Sáenz Rovner, professor of Faculty of Economics at National University (Universidad Nacional). He's attempting to clarify misconceptions about cannabis use in Columbia & the influences the United States had in that country.

a few excerpts from his writings (translation by Scielo (Sky)) (it's a better read in Spanish, but the English translation does not detract from the points being made. I've made a few clarifications from the Sky version):

regarding "Early Prohibition

Marihuana consumption was not considered as being a public health problem in the USA until the 1930s. Until then it was perceived as being a vice only affecting ethnic minority groups, bohemians, jazz musicians, sailors and other marginal elements in society. A US government report stated that marihuana use in the USA, "was noted, particularly amongst Latin-Americans and the Spanish-speaking population. Cannabis cigarettes are sold on a large scale in the states on the frontier (border) with Mexico and in the cities of the south-east and south-west, the same as in the city of New York and, in fact, wherever there are colonies of Latin-Americans" (Federal Bureau of Narcotics 1930, 15 and Musto 1993, 248-254).

When it began to be reported that young Anglos were smoking "weed" then pressure became applied by groups of educators and religious communities to have the practice declared illegal. The Federal Bureau of Narcotics (FBN), the north-American federal agency responsible for repressing drug trafficking, was behind efforts aimed at criminalising marihuana, making public statements that it was a drug which induced violence amongst those who smoked it. Such pressure was successful when President Franklin D. Roosevelt sanctioned the Marihuana Tax Act in August 1937 criminalising its sale as being a federal crime (Himmelstein 1983 58-71; Morgan 1981, 138-142; Walter 1989, 99-107).

Curiously, and perhaps due to recent legislation and strong campaigns against it in the USA, marihuana's effects were described in worse terms than those of other drugs. Harry Anslinger (FBN director) declared that, "Prolonged marihuana use ... usually leads to insanity, the same as crime" (Jonnes 1996, 160), and added that, "fifty percent of violent crimes committed in districts inhabited by Mexicans, Spanish people, Latin-Americans and Greeks can be traced to this evil ... the worst of evils" (Speaker 2004, 215). The medical specialist, Lawrence Kolb, has stated that, "... marihuana is a dangerous drug, much more harmful, in certain aspects, than opium" (Musto 1972). Kolb emphasised that, "... an alcoholic, a marihuana consumer, causes many crimes," during a congress organised by the FBN in December 1938 - Marihuana Conference 1938.

Colombian authorities had already noticed the existence of marihuana-growing in 1925, the same as its consumption by sailors, stevedores (longshoremen) and prostitutes in the ports (Ruíz Hernández 1979, 111). However, a similar effect in Colombia was only felt as a result of pressure against marihuana and its recent banning in the USA. For example, the Revista de Higiene (the Ministry of Health's official organization) published an article by Kolb in September 1939 entitled, "Marihuana: the weed which drives you mad." 2 Even though measures related to marihuana had already existed in Colombia since the 1920s (Sáenz Rovner 1997, 5; López Restrepo 2000, 91), the Colombian government absolutely prohibited marihuana-growing. It ordered the destruction of existent plantations and established that those who violated this disposition would be sanctioned, "as illegal traffickers in drastic drugs ... according to the penal code."3

It should be remembered that campaigns against marihuana replicated debate relating marihuana to violence and crime in countries such as Cuba (Sáenz Rovner 2005, 55-56). Heated debate took place in México, whilst the newspaper Excelsior stated that many crimes were committed, "under the pathological influence of marihuana." High government functionaries questioned the official north-American view and even proposed treatment (not punishment) for those addicted to other drugs. Pressure applied by Anslinger and the US government led to an embargo being imposed on selling legal drugs to México, the Mexican government, in turn, opting for repressing consumers (Walker 1989, Astorga 2003)."

I'll posts more the further along I get.

the backstory (my translation):

What began as research into the economics of Columbian businessmen, Mr. Rovner stumbled upon documents in the United States regarding the topics "Columbia. Narcotics." He found these documents which chronicled the "recipe" for governmental prohibition & propaganda of marijuana interesting. They documented the first captures of Columbians, records of cultivation & drug routes, But what awakened his curiosity was the discovery of official pages written in 1956 about the capture of two of his cousins, Rafael y Tomás Hernán Olózaga. He then felt compelled to dive headlong into the investigation.

"Aquellos documentos equivalían a una especie de prehistoria del narcotráfico. Páginas oficiales sobre las primeras capturas de colombianos en el exterior. Registros sobre cultivos. Rutas para traficar. Pero entre todo aquel material, lo que más despertó su curiosidad fue enterarse de que en 1956 dos hermanos colombianos fueron capturados en La Habana acusados de traficar con drogas. Lo que hacía atractiva aquella historia eran los lazos familiares de los capturados. Rafael y Tomás Hernán Olózaga eran primos hermanos de Hernán Echavarría Olózaga, famoso industrial antioqueño. Más aún, por línea paterna eran descendientes de dos ex presidentes, Tomás Cipriano de Mosquera y Pedro Alcántara Herrán. Decidió seguirles la pista."