Why were the residents of florida concerned about the united states annexing cuba?

In 1898 Cuba was a geopolitical aberration. Lying only 90 miles from the Florida keys, astride the entrance to the Gulf of Mexico, it was separated from Spain by the vast expanse of the Atlantic Ocean. Yet Cuba remained one of Spain's two colonies in the New World. (The other was Puerto Rico.) It was governed from Madrid much as it had been governed since it was first occupied and settled by the Spaniards in 1511.

Not that Cubans were as compliant in 1898 as they had been during most of the colonial period, especially when the other Spanish Americans severed their ties with the mother country in the 1820s. At that time Cuba was evolving from a slowly growing colony into the world's leading sugar producer, a development that required the importation of steadily increasing numbers of African slaves. As a result, by 1840 there were in the island approximately 430,000 slaves, approximately 60 percent of the population was black or mulatto. Fearing a repetition of the upheaval that wiped out Haiti's white planter class in 1791, Cuban creoles (native born Cubans of European descent) refrained from imitating their mainland counterparts and risk all in a bloody and ruinous confrontation with the metropolis' military might.