Manatee Genealogical Society published a book in 1985  titled  Extractions from Manatee County Censuses of 1860 - 1870 - 1880 - 1885 – 1895. 1  In this book,  Manatee County History for the early years of 1842 through 1889 was provided. This material is presented here for the researcher to appreciate the beginnings of the migration to Manatee county and some of the early settlers. The history information is organized and chronicled by era (1842 through 1889)
Use the following Links to navigate through Manatee early history.  
The first settler of Anglo-Saxon decent was reportedly, Josiah Gates, an innkeeper from Fort Brooks (present day Tampa). He arrived in the spring of 1842 with his family. He built a large house, a cabin for a slave family, and enclosures for his animals. Around this complex he built a fence of pine logs, positioned vertically, as a protection from wild animals or stray Seminoles. The main building was used as the family living quarters, and it was also a halfway house where new settlers stayed temporarily while their new homes were being built.
The Gates' near neighbor was Henry Smith Clark, who established the first store and dock. After a few years he had a schooner built named "Atlanta." Her maiden voyage was to New York with a cargo of sugar and molasses. Tragedy struck on the return trip when the ship laden with merchandise suffered the brunt of the storm of 1848 and sank. Captain William Gamble, a brother of the owner of Gamble Plantation and some of the crew members were lost. 
Another settler, Dr. Joseph Braden, came from Tallahassee with his brother, Hector W. They were wealthy tobacco planters who came to this area after the panic of 1837. Their original intent was to raise tobacco, but this plan was discarded in favor of planting sugar cane.  About this same time, Ezekiel and Abigail Glazier arrived. They were natives of Massachusetts who had settled temporarily in Ohio and from there traveled to Florida. Mr. Glazier was a cabinet maker and he built his home and some of the furniture. He also built other houses and buildings. He acquired 160 acres through the Armed Occupation Act of 1842, a short-lived act nullified in 1845 when Florida became the 27th state. Persons applying for land under this act had to meet the following requirements: be at least 18 years old, be able to bear arms, must clear five acres of land, and must build a habitable dwelling and reside in it for five years. Additional land was offered for sale at $1.25 an acre.
Major Robert Gamble, son of a wealthy tobacco grower from Tallahassee, is said to have arrived here about 1844. He purchased 3,500 acres of land for $10,000. He built a large house and established a sugar cane plantation. (The plantation house has been restored and is now the Judah P. Benjamin Confederate Memorial.)
The Atzeroth family arrived here from Bavaria, via New York, Pennsylvania, and New Orleans, seeking a place where Mrs. Atzeroth could enjoy improved health. They settled in 1843-44 on Terra Ceia Island on land acquired through the Armed Occupation Act.  Rev. Edmund Lee was the first minister (ordained Presbyterian). He and his wife, Electa, came from Vermont also to improve his health. Shortly after their arrival in 1845-46, they opened the Dame School for Boys.
There were other families who came, however, the ones mentioned here give the general idea why this section was settled. The people were attracted by the inexpensive land, the mild climate, the fertile soil, and the waterways that were teeming with fish and that also provided routes for travel.
1.  Reference (Book): Extractions from Manatee County Censuses of  1860 - 1870 - 1880 - 1885 - 1895, by Mabel Schneider (Chairman), Lucille Ford, Paul Rehnborg, Elinor Rehnborg, Helen Richeson & Peggy Wetsel - Members of the Manasota Genealogical Society, published by the Manasota Genealogical Society Inc., copyright 1985, all rights reserved, 343 pages