The National Conference of State Legislatures keeps track of statutes and citations at the state-level which relate to this. According to the NCSL web site:
Several states have enacted laws addressing access to email, social media accounts, microblogging or other website accounts, or certain electronically stored information, upon a person’s incapacity or death. Nevada law provides for the termination of decedents' social media accounts.The information on the NCSL web site is up-to-date and includes information on legislative actions in 2016. If this is a topic of interest to you, then check out the site.