Hernando de Escalante Fontaneda related that a sailor from the Bay of Biscay, called the Viscayno or Biscayno, had lived on the lower east coast of Florida for a while after being shipwrecked.

They provided the only access for ocean-going vessels to Biscayne Bay until artificial channels were dredged starting early in the 20th century.

In the early 19th century, African-American slaves and Black Seminoles escaped to the Bahamas from Cape Florida to evade American slaver catchers.

In 1820, one traveler reported seeing 60 "Indians", 60 "runaway slaves", and 27 boats of Bahamian wreckers preparing to leave Cape Florida.

In a short period before the Cape Florida lighthouse was built in 1825, an estimated 300 Black Seminoles found passage from Key Biscayne to Andros Island in the Bahamas on seagoing canoes and Bahamian boats, settling at Red Bays and Nicholls Town.

Although Key Biscayne was less suitable as a departure point after the lighthouse was built, the Bahamas remained a haven for escaping slaves.

Mary and William sold three acres (about one-and-a-quarter hectares) of their newly acquired land at the southern tip of the island (Cape Florida) to the U.S. government for US$225.

[26] While the war against the Seminoles continued, Mary and William Davis made plans to develop a town on Key Biscayne.

A complication arose when Venancio Sanchez of St. Augustine purchased for US$400 a half share in the old Fornells grant from another surviving heir, who lived in Havana.

[27] The numerous ship wrecks that occurred along the southeast coast of Florida from Key Biscayne to the Dry Tortugas was a cause for concern.

In a report written by Lieutenant Colonel Robert E. Lee in March, 1849, the Board recommended that Key Biscayne be made a military reservation.

[31] From 1888 to 1893, the Cape Florida lighthouse was leased by the United States Secretary of the Treasury for a total of US$1.00 (20 cents per annum) to the Biscayne Bay Yacht Club for use as its headquarters.

[32] In 1898, in response to the growing tension with Spain over Cuba, which led to the Spanish–American War, the Cape Florida lighthouse was briefly made U.S. Signal Station Number Four.

[37] In the 1880s, Ezra Asher Osborn and Elnathan T. Field of New Jersey started an enterprise to develop the Florida coast from Key Biscayne to Jupiter by clearing native vegetation, leveling Indian midden mounds and beach dunes, and planting coconuts.

As a result of their efforts, in 1885 Osborn and Field were allowed to purchase Key Biscayne and other oceanfront land from the Florida Internal Improvement Trust Fund for 70 cents an acre.

Venancio Sanchez still claimed a half share of the Fornells Grant, two of the town lots had been sold to William Harney around 1840, and Osborne and Field had their deed from the Florida Internal Improvement Fund.

It was a two-story cottage with five bedrooms and verandas on three sides, raised ten feet above the ground on pilings to protect against storm surges.

Before mail service to the Miami area improved, Munroe would camp out on Key Biscayne every Tuesday evening so that he could sail out to the edge of the Gulf Stream early Wednesday morning to retrieve a package of newspapers and magazines dropped for him in waterproof pouches by a passing steamship.

[42] In 1902, William John Matheson, who had made his fortune in the aniline dye business, visited Biscayne Bay on his yacht.

In 1908 Matheson began buying up the property on Key Biscayne north of the Davis holdings, all the way to Bear Cut, over 1,700 (about 690 hectares) acres.

Although Matheson bid on the property, Munroe arranged a sale, for US$20,000, to James Deering, the International Harvester heir and owner of the Villa Vizcaya estate in Miami.

Patient legal work eventually convinced the U.S. Congress and President Woodrow Wilson to agree to recognize Matheson's and Deering's ownership of Key Biscayne.

[47] In 1920, the heirs of Venancio Sanchez filed a lawsuit against James Deering, claiming an undivided half interest in his Cape Florida property.

In March 1926, the U.S. government auctioned off some lots on Key Biscayne that had been retained when the rest of the island was transferred to the State of Florida.

[54] The Attack on Pearl Harbor and the entry of the United States into World War II stopped all work on the causeway and the development of Virginia Key.

The causeway was named for Eddie Rickenbacker, a World War I flying ace, and founder and president of the Miami-based Eastern Air Lines.

[56] The residents of Key Biscayne successfully petitioned the Dade County Commission allow a referendum on incorporating the community.

[57] In 1948, José Manuel Áleman, who had fled Cuba in the wake of scandals surrounding his service as education minister under Ramón Grau San Martín, bought the Cape Florida property from the Deering estate.

With the prospect of a major highway passing through his property, Áleman rushed to prepare it for development: he had it completely cleared, leveled and filled in.

[62] In 2004 a sign was installed to commemorate the site as part of the National Underground Railroad Network to Freedom Trail, for the Black Seminoles who escaped to the Bahamas.