Original logo (1920s) 
 Updated logo (1940s) 
The word the is removed from the logo (1950s)
Corporation is eliminated from the logo (1960s)
Big re design (1980s) 
R icon is created (1995)  
A lot of extra detail and effects added (2001)   
...and it is simplified and flattened again (2011)   
 

 
 
 
  
  
  
  
 