Potency is measured by the levels of psychoactive cannabinoids present in individual plant samples.
Beginning in the 1970s, most cannabis was imported illegally from source countries. From growing time to transportation to distribution, cannabis was, on average, much older due to the time it took to get from farm to consumer.
Enter research and knowledge that began to change the game! In the ’70s, much of the cannabis brought in to the U.S. was a mixture of various parts of the plant. This means that when people used cannabis, they were not using the plant parts high in THC.
When hydroponic systems came into the picture in the 1980s, Americans began to grow discretely in their basements. This new ability to produce cannabis on a local level led to a boom in higher quality, fresher strains.
Now the potency of marijuana continues to increase as research continues and the cannabis industry becomes more high tech than ever.