what was the first superhero crossover

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
what was the first superhero crossover	1.06	0.3	6989	71	38
what	1.66	0.5	5780	35	4
was	0.08	0.4	8062	95	3
the	1.86	0.9	8817	85	3
first	0.68	0.4	680	37	5
superhero	1.54	0.4	616	44	9
crossover	0.77	0.3	5413	27	9

Keyword	CPC	PCC	Volume	Score
what was the first superhero crossover	0.45	0.9	467	31
what was the first superhero comic crossover	1.2	0.3	7722	43
what was the first crossover	0.68	0.3	6302	4
when was the first comic crossover	1.96	1	5103	79
what was the first superhero	0.79	0.2	3024	2
what was the first superhero ever created	1.95	0.1	4908	24
first comic book crossover	0.17	0.6	1065	81
when was the first superhero made	1.48	0.6	4107	43
superhero in transformers crossover	0.58	0.1	5018	95
was there ever a marvel dc crossover	1.08	0.7	5213	75
first superhero in history	0.06	0.1	1734	9
longest superhero crossover event	0.97	0.8	659	37
superheroes starring in crossover events	1.28	0.1	2699	58