To evaluate a historical primary source, such as a political cartoon, remember the acronym OPVL:

Origin: Who created or wrote it? What is it? When was it made? Where did it come from?

Purpose: Why was the source created? What is the author/illustrator trying to show? Is he/she trying to convey a message, persuade a population, make a point? What sort of influence would it have had?

Value: What can a historian gain from examining the source? Are there any facts included, or is it an opinion? What does it say about the creator and his/her time period? Does it show a popular opinion?

Limitations: What are the limits of the source? What should one be wary of when examining it? Is it factual, or opinionated? Is it propaganda, or a biased depiction? Is the intent clear?