With the passage of the Illinois Cannabis Regulation and Tax Act in 2019, Illinois became the first state in the nation to legalize recreational sales by an act of the state legislature, as previous states had legalized sales by voter initiatives. Vermont legalized recreational use, but not sales, through its legislature. At full maturity, Illinois is expected to generate between $2 to $4 billion in annual revenues from recreational sales. A first in the nation, Illinois will also expunge an estimated 700,000 marijuana-related police records and court convictions in a phased approach forecast to be completed by 2025. Retail sales from recreational cannabis in Illinois average an estimated $40 million in revenue each month since legalization.
Since 2014, the Illinois Medical Cannabis Patient Program (MCPP) has also enrolled over 143,000 qualifying patients in the state's medical cannabis and opioid alternative programs across 55 dispensaries offering a lower tax rate when compared to recreational transactions. Retail sales from the medical programs alone have topped nearly $790 million to date.
In 1931, Illinois prohibited recreational use of cannabis, as part of a nationwide trend across 29 states in the early 20th century.
Cannabis Control Act (1978)
Illinois passed the Cannabis Control Act in 1978, which technically allows for medical marijuana. However, in order for it to become an actuality, action was required from two state departments: Human Services and the State Police. Neither department took action.
Medical cannabis (2013)
The Illinois General Assembly passed the Compassionate Use of Medical Cannabis Pilot Program Act in 2013 (MCPP). The law legalizes the use of medical cannabis in tightly controlled circumstances. In August 2013, Governor Patrick Quinn signed into law the state's medical marijuana program, which would take effect on January 1. making it the 20th state to do so.
"Legally registered patients" may, with a prescription from a medical caregiver, apply for an ID card that allows the use of marijuana for medical purposes. The law lists over 30 specific medical conditions that may be legally treated using cannabis, and allows the Department of Public Health to add other conditions to the list via administrative rulemaking. Applications for patients, growers, and vendors began in September 2014.
As of October 2020, the Medical Cannabis Patient Program had significantly grown to over 143,000 qualifying patients participating in the state's medical cannabis and opioid alternative programs.
In July 2016, Illinois reduced punishment for under 10 grams of cannabis to a $100–200 fine; it was a misdemeanor previously. The law also sets the requirement for DWI at 5 nanograms/ml of THC in the blood.
Proposed recreational use (2017)
On March 22, 2017, Illinois lawmakers proposed legalizing recreational marijuana in the state. The measure would also allow residents to possess up to 28 grams of cannabis, or about an ounce, and to grow five plants. Early estimates found that legalized marijuana would generate between $350 to $700 million in annual sales. The Chicago Tribune reported legislation was "widely expected to pass" in 2019, following election of pro-legalization governor JB Pritzker and a favorable state legislature.
Medical cannabis expansion (2018-2019)
On August 28, 2018, Illinois' medical cannabis program greatly expanded becoming available as an opioid painkiller replacement. The legislation also eased the application process as applicants will no longer have to be fingerprinted or undergo criminal background checks. Some estimate the expansion could bring in up to 365,000 new patients into the medical marijuana program generating an additional $425 million in revenue for the state.
On August 12, 2019 Governor J.B. Pritzker signed into law legislation that once again expands Illinois' medical cannabis program and also makes it permanent. The new law adds an additional 11 conditions to the existing program including chronic pain, anorexia nervosa, autism, Irritable bowel syndrome, migraines, osteoarthritis, Ehlers-Danlos syndrome, Neuro-Behcet's autoimmune disease, neuropathy, polycystic kidney disease, and superior canal dehiscence syndrome. When recreational marijuana becomes legal in January 2020, taxation for medical cannabis products will remain at 1%.
Recreational legalization (2019)
On May 31, 2019 the Illinois General Assembly passed the Illinois Cannabis Regulation and Tax Act to legalize recreational marijuana use starting on January 1, 2020. The bill was signed by Governor J.B. Pritzker on June 25, 2019. Recreational-use revenue in Illinois is expected to reach an estimated $1.6 billion a year. Illinois became the first state in the nation to legalize cannabis for recreational sale through a state legislature rather than ballot initiative. Overall, Illinois is the 11th state in the US to allow recreational marijuana.
An estimated 700,000 Illinoisans will qualify for the expungement of past marijuana-related convictions. The state, in partnership with the Illinois State Police, expects to fully complete the process by 2025. To date, Illinois was the first state in the nation to include the social equity centric provision.
On January 1, 2020, the first day of legal recreational sales, over 77,000 customers spent $3.2 million in legal sales at dispensaries across Illinois. These figures were historic as no other state, Oregon being second, has generated such significant first day recreational sales. Dispensaries saw long lines across the state with customers coming from across the Midwest and nation. On January 6, 2020, Governor Pritzker's office announced that in the first five full days of recreational adult-use sales, 271,169 individual transactions totaled over $10.8 million in sales statewide. Total sales for January 2020 approached $40 million, despite supply shortages.
In addition, more than 700 applications were submitted for the second round of newly awarded dispensary licenses, scheduled to be announced on May 1, 2020; over 600 were considered "social equity" applicants which meet certain criteria to benefit historically disenfranchised communities.
Cultivation of Cannabis
Under the Illinois Cannabis Regulation and Tax Act, which took effect on January 1, 2020, stipulated that medical marijuana patients could grow up to five plants at a time in their home or on their property. However, recreational users cannot grow marijuana in their home nor on their premises at all. A violation of this stipulation is a civil penalty of 200 dollars. In regards to cultivating cannabis commercially, only Illinois' existing licensed medical marijuana facilities were able to grow the crop initially. However, in 2020 "craft growers" will be able to apply for licenses to cultivate cannabis for commercial use for no larger than 5,000 square feet of crop. 
- "Long lines, celebrations mark first hours of recreational marijuana sales in Illinois". Chicago Tribune. Retrieved 2 January 2020.
- "Illinois's Legal Cannabis Sales Reach $3.2 Million on First Day". www.bloomberg.com. Bloomberg. Retrieved 2 January 2020.
- "How Is Marijuana Expungement Working In Illinois?". NPR. Retrieved 5 January 2020.
- McCoppin, Robert. "Illinois recreational marijuana sales set another record in May with more than $44 million in transactions despite the coronavirus". chicagotribune.com. Retrieved 14 June 2020.
- "MCPP Update – October 6, 2020 - Medical Cannabis Pilot Program". www2.illinois.gov. Retrieved 18 October 2020.
- "OAPP Update – October 6, 2020 - Medical Cannabis Pilot Program". www2.illinois.gov. Retrieved 18 October 2020.
- Also from Bruce Rushton (2012-02-09). "The war on weed". Illinoistimes.com. Retrieved 2016-11-11.
- "Medical Marijuana Is Already Legal in Illinois".
- "720 ILCS 550/ Cannabis Control Act".
- "Medical Cannabis Pilot Program". Illinois Department of Agriculture. 2014. Retrieved September 6, 2014.
- Johnson, Carla K. (January 21, 2014). "Illinois Medical Marijuana Rules Unveiled". NBCChicago.com. NBC Universal Media. Retrieved September 6, 2014.
- "Illinois governor to sign medical marijuana bill today". Articles.chicagotribune.com. 2013-08-02. Retrieved 2016-11-11.
- Illinois Department of Agriculture.
- "Rauner reduces punishment for minor pot possession from jail to citation". Chicago Tribune. 2016-07-29. Retrieved 2016-11-11.
- "Illinois is latest state to decriminalize small amounts of marijuana". July 30, 2016.
- McCoppin, Robert. "Illinois lawmakers propose legalizing recreational marijuana". chicagotribune.com.
- Robert McCoppin (March 22, 2018), "Marijuana referendum could strengthen movement to legalize in Illinois, but naysayers say ballot question unfair", Chicago Tribune
- Robert McCoppin (November 9, 2018), "With Pritzker win, pot legalization is now in legislators' hands, but not all are on board", Chicago Tribune
- McCoppin, Robert. "Rauner signs medical marijuana expansion bill allowing drug as painkiller alternative". chicagotribune.com.
- "Chart: Medical cannabis as alternative to opioids could give Illinois' MMJ program a massive boost". Marijuana Business Daily. 25 June 2018.
- Munks, Jamie. "New law broadens access to medical marijuana, makes state program permanent". chicagotribune.com. Retrieved 13 August 2019.
- Schuba, Tom (12 August 2019). "Pritzker makes medical marijuana program permanent, adds list of new conditions". Chicago Sun-Times. Retrieved 13 August 2019.
- Petrella, Dan. "Illinois House approves marijuana legalization bill backed by Gov. J.B. Pritzker". chicagotribune.com. Retrieved 1 June 2019.
- "Illinois posed to legalize marijuana sales, expunge criminal records for pot crimes". USA TODAY. Retrieved 1 June 2019.
- "Looking forward to legal weed? Here's a Q&A about Illinois' marijuana legalization". Belleville News-Democrat. June 7, 2019. Retrieved 2019-06-09.
- "Illinois marijuana growers plan hiring binge". Crain's Chicago Business. 3 June 2019. Retrieved 7 June 2019.
- "Illinois Lawmakers Approve Marijuana Legalization". U.S. News & World Report. Retrieved 1 June 2019.
- Illinois becomes 11th state to allow recreational marijuana Associated Press, June 25, 2019
- McCoppin, Robert. "Getting marijuana convictions expunged in Illinois: What you need to know about the process". chicagotribune.com. Retrieved 5 January 2020.
- Marotti, Ally. "Nearly $3.2 million in legal weed was sold in Illinois on the first day of sales, and the long lines continue". chicagotribune.com. Retrieved 2 January 2020.
- "Illinois News - Illinois.gov". www2.illinois.gov. Retrieved 7 January 2020.
- Marotti, Ally (2020-02-04). "Customers bought nearly $40 million in recreational marijuana during the first month of sales in Illinois". chicagotribune.com. Retrieved 2020-02-05.
- "WHAT YOU NEED TO KNOW ABOUT MARIJUANA LEGALIZATION IN ILLINOIS". Illinois Policy.