Complex sentence: The importance of the cigar industry to Tampa's economy had waned by the 1950s, so when minor league baseball returned to the city in 1957, the new team was called the "Tampa Tarpons".
Split into simpler sentences: The importance of the cigar industry to Tampa's economy had waned by the 1950s. When minor league baseball returned to the city in 1957, the new team was called the "Tampa Tarpons".