I live in San Francisco, California.  Senior citizens who are at least age 65 and whose annual household income does not exceed a specific amount are able to ride public transit for free. 
I am a senior citizen and I live alone.  I ride public transit for free because my annual household income is below 89,650 dollars.  
Two senior citizens who share a household qualify for free public transit if their annual household income is below 102,500 dollars.  
    
