Walgreens

198?–1993
In the 50's, Walgreens redesigned their logo. The pestle was added later in the late 80's.

1993–2006
In 1993, Walgreens changed the red pestle to the blue pestle and added The Pharmacy America Trusts slogan.

2006–present
The logo was slightly stretched and slenderized in 2006, and the pestle was omitted.