Westchester County covers an area just over 457 square miles. Its geographical setting is a favorable one, with Long Island Sound on the east and the Hudson River on the west. The terrain is largely rolling hills, intersected by three main streams- the Croton, Bronx, and Saw Mill rivers. The county is one of the most heavily forested in New York State. It has retained much of its rural character while adopting the urban and suburban lifestyles dictated by its proximity to New York.

European exploration of the region began with the voyages of Verrazano in 1524 and of Hudson in 1609. Both these explorers were simply looking for a water route to Asia. But the beauty and rich resources found by the early explorers soon brought other Europeans to settle in the area. The abundance of wildlife, particularly beaver, drew many settlers to Westchester. As Westchester's earliest historian, Adriaen Van der Donck, wrote, "Eighty thousand beaver are annually killed in this quarter of the country, besides elk, bears, otters, deer and other animals" (Van der Donck, A Description of the New Netherlands). Some Europeans did their own trapping, but most traded blankets, hatchets, glass beads, and other merchandise for beaver trapped by the local Indians. One of the most successful of these early traders was the Dutchman Jan Peek, for whom the city of Peekskill is named.

The Indians of Westchester were members of the Algonkian tribes. They were generally more peace loving than the fierce Iroquois, who lived in northern New York. They lived on the bounty of their land. They hunted and fished, and grew crops of corn, beans, and pumpkins. Following the seasons, they spent the summers on the shores of the Long Island Sound and Hudson River, and moved to inland homesites during the colder months. They gathered oysters and other shellfish in summer to be smoked and dried to add to their winter food supply.

The seventeenth-century explorers and settlers found several Indian villages in Westchester. They described the Indians they saw as "well proportioned .... Their limbs are properly formed, and they are sprightly and active" (Van der Donck, A Description of the New Netherlands). They had straight black hair, dark eyes, and swarthy skins. They had strong physical constitutions and were rarely deformed or sickly.  

The first permanent white settlers of Westchester County were Dutch, who, in the middle decades of the seventeenth century, began to occupy the Hudson Valley between their earlier settlements in New Amsterdam (now New York) and Fort Orange (now Albany).

Settlement was sponsored by the Dutch West India Company. It became especially attractive after 1638, when William Kieft was appointed director-general of the Dutch colony, and the company liberalized the conditions of colonization, giving anyone the right to hold land, even foreigners. Kieft began acquiring land in what is now Westchester and the Bronx in 1639, and the area soon began to be settled and developed.  

Conflict with the Indians arose almost immediately. The Indians sold about twenty-five tracts of land during the colonial period, but they had no conception of property ownership comparable to that of Europeans. In their view, they "owned" the land of Westchester simply by living on it. When the white men offered knives, tools, clothing and blankets iron kettles, tobacco, beer, and rum in return for land, they expected exclusive possession. The Indians were not really aware of what they were giving up until it was too late.  

Intermittent warfare between the Indians and the Dutch and English was to continue for several years. The bloodshed was climaxed by John Underhill's raid on an Indian village near present-day Bedford in 1644, effectively crushing Indian resistance. On August 30, 1645, a general peace treaty was signed between the Dutch and Indians of the Hudson Valley area. War casualties, combined with the diseases brought by the Europeans, greatly diminished the Indian population. While Indians remained for years on the lands they had sold, they gradually disappeared. By 1800 there were very few still living in Westchester.

In the 1640s the English began to move west from their New England settlements to occupy land in what is now Westchester and the Bronx. For two decades the English and Dutch struggled for control over the area, but by 1664 the Dutch were forced to surrender the whole New Netherlands colony.  

Many of the English colonists came to America seeking religious and economic freedom. The earliest English settlements in Westchester County were the villages of Westchester (later called the Borough of Westchester, and now part of the Bronx), Rye, Mamaroneck, Eastchester, and Bedford. In the 1680s Huguenots, French Protestants who had been persecuted in their homeland, also came to Westchester to find religious freedom.  

At the same time that the English towns were being developed, large tracts of Westchester land were being established as so-called "freehold" manors. The manor proprietors could lease land to tenants or sell it to them outright. Although a proprietor was called "lord of the manor," he was not a "Lord" in the sense of British nobility. There were six manors established in Westchester: Pelham, Fordham, Philipsburgh, Morrisania, Cortlandt, and Scarsdale. 

The manor owners had to do a good deal more than just collect rents. They were required to build mills for their tenants; to survey lots and provide livestock for the farms; to provide mechanics, millers, boat builders, and, if possible, a doctor, a clergyman, and a schoolmaster.

Caleb Heathcote, lord of the manor of Scarsdale, was also one of the proprietors of what were called the Three Great Patents. Most patents were tracts of land granted to groups of associates, rather than individuals, to develop through lease or sale. Tenant families on both manor and patent usually held their land for generations.  

On November 1, 1683, the county of Westchester was created by an act of the New York General Assembly. The county at this time was still largely wilderness, and the life of its settlers was primitive. Nearly everything they consumed was raised or made on their farms. Grains, vegetables, fruits, and livestock were the chief products. Flax was an important crop, and every home had its spinning wheels for the making of linen and wool thread. Wood, cattle, and food were bartered for the necessary items that could not be produced at home.  

There were only a few roads in colonial Westchester, and they were very poor. The best means of transportation was by water. Sloops on the Hudson River and Long Island Sound carried a brisk traffic of both passengers and produce, but people living in the interior were quite isolated. In the villages, town meetings were important occasions, and in settlements both large and small, the church was the center of the community life. Colonial churches not only served as religious centers, but also played an important social and political role.  

The eighteenth century brought some advancement in the standard of living. The lords of the manors lived extremely well, and their tenants, as well as the small independent landowners, gradually improved their homes and land. Some local cottage industries developed in the area, particularly shoemaking and the crafting of furniture. Roads began to be improved, and ferries and taverns established, as travel became more common. 

By 1775 Westchester was the richest and most populous county in the colony of New York. It was still almost entirely farmland, dotted with small villages at crossroads and on the waterways. Westchester farmers did not riot over taxes as their neighbors in the New England colonies did; British markets and protected prices for agricultural products were of more importance to them.  

Once the revolution began, however, Westchester saw more fighting and suffering than any other area in the country. From 1776, when Washington and his troops retreated through Westchester after their defeat on Long Island, until 1783, when the British were finally expelled, the county was a battleground. For Westchester, the Revolution was truly a civil war, as families were often divided between patriot and loyalist sympathies.

After the Battles of Pelham and White Plains in October 1776, the main American headquarters was at Continental Village, just north of Peekskill. The British headquarters was in New York City. Westchester became the war "Neutral Ground" between the two camps. During the entire course of the war, the farmers and townspeople throughout Westchester were subjected to raiding, pillaging, and destruction by both British and American irregulars.  

The capture of Major John Andre`, the British spy, by three Westchester men, was an important factor in America's ultimate victory, for it saved West Point, the fortress protecting the Hudson River, from seizure by the British. Westchester also saw the French troops, commanded by Rochambeau, pass along its roads as they came from Rhode Island to help Washington's army defeat the British at Yorktown in 1781. In 1783, after seven years of suffering, Westchester's countryside was devastated and its population depleted. Recovery from the war would take time and hard work.