The significance of the 1920's political cartoon with the phrase "what a friend we have in Coolidge" is that Coolidge was running for president at the time and he wanted to seem more friendly and relatable.
The cartoon shows a series of men dressed in suits standing around a register with a $ symbol and the phrase says “What a friend we have in Coolidge”. The cartoon means that the American industrial and commercial leaders approved Coolidge administration and policies because it brought them profit.