Cannabis use started to become popular in the United States in the 1970s.[252] Support for legalization has increased in the United States and several U.S. states have legalized recreational or medical use.[282] A 2018 Social Science Research study found that the main determinants of such changes in attitudes toward marijuana regulation since the 1990s were changes in media framing of marijuana, a decline in perception of the riskiness of marijuana, a decline in overall punitiveness, and a decrease in religious affiliation. [283]