Sick hours are mandated by law in SanFran and Seattle - some other locales offer this too though these two cities are the most strict in the entire country. In Seattle the ordinance is called "PSST" (Seattle Paid Safe and Sick Time) and accrual is one hour for every 30 hours worked. Additionally, by law any absences covered under the PSST ordinance are not to counted against your attendance record. Ex: if you are only out due to PSST time taken or via a regularly scheduled/approved vacation then you still have perfect attendance. As far as usage, it can only be used in place of a normally scheduled shift. Normal call-out procedures apply (2 hours in advance, etc) and on the sick time request form you are to reference the ordinance which can be done simply by entering "Seattle PSST" or similar within the "reason" section.
SanFran is similar and other locales may too have similar systems though none are as "progressive" or employee-centric as these two cities. Interestingly, the Seattle ordinance (and I think SanFran too) is covered under the local civil rights laws.
As far as other locations I've heard some do not accrue sick time while others due but at varying rates. Meh ... go figure. Available sick time hours are listed on your pay stub within the same section as vacation time ... at least in this region.