One of the unknown reasons why weed is illegal is because of its cousin hemp which was hated by many paper product companies of the time due to its large usability low cost and did less impact on the environment. Well one of the large paper companies was not happy with hemp becoming so large and they decided to air commercials to say that weed, hemps cousin, was bad for your health. They then got it to the congress and made them believe that it was bad for u and cannibas was bad for u. Well they passed a law basically sayin that all cannibas products are illegal in the states and that stopped hemp but it also stopped weed. Just to let u know this may not be 100% correct info it's just something i found when i was researching it Smoke weed everyday
Weed is illegal because government wants to control you, they don't want you to break your metaphorical shackles.
Also, harry anslinger, who was in charge of narcotics control, was pressured by some to include marijuana. He originally didnt want to mess with it because of how difficult it would be to control an easy to grow plant. He eventually caved and later turned hardcore agianst weed and touted the evils of this terrible afront to the peace of man. Later richard nixon, agianst the reccomendations of his own staff who told him they should decriminalize, demanded going to war agianst this horrific plant. Thanx nixon you piece of shit. So we see multiple reasons why its federally illegal and why its been such a hard road to change