In 1902, the first modern electrical air conditioning unit was invented by Willis Haviland Carrier in Buffalo, New York. After graduating from Cornell University, Carrier, a native of Angola, New York, found a job at the Buffalo Forge Company. While there, Carrier began experimenting with air conditioning as a way to solve an application problem for the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York, and the first "air conditioner", designed and built in Buffalo by Carrier, began working on 17 July 1902.
 
Designed to improve manufacturing process control in a printing plant, Carrier's invention controlled not only temperature but also humidity. Carrier used his knowledge of the heating of objects with steam and reversed the process. Instead of sending air through hot coils, he sent it through cold coils (ones filled with cold water). The air blowing over the cold coils cooled the air, and one could thereby control the amount of moisture the colder air could hold. In turn, the humidity in the room could be controlled. The low heat and humidity helped maintain consistent paper dimensions and ink alignment. Later, Carrier's technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet rising demand. Over time, air conditioning came to be used to improve comfort in homes and automobiles as well. Residential sales expanded dramatically in the 1950s.
 
In 1906, Stuart W. Cramer of Charlotte, North Carolina was exploring ways to add moisture to the air in his textile mill. Cramer coined the term "air conditioning", using it in a patent claim he filed that year as an analogue to "water conditioning", then a well-known process for making textiles easier to process. He combined moisture with ventilation to "condition" and change the air in the factories, controlling the humidity so necessary in textile plants. Willis Carrier adopted the term and incorporated it into the name of his company. The evaporation of water in air, to provide a cooling effect, is now known as evaporative cooling.
 
Evaporative cooling was the first real air-conditioning and shortly thereafter the first private home to have air conditioning (The Dubose House) was built in Chapel Hill, North Carolina. Realizing that air conditioning would one day be a standard feature of private homes, particularly in the South, DuBose designed an ingenious network of ductwork and vents, all painstakingly disguised behind intricate and attractive Georgian-style open moldings. Meadowmont is believed to be one of the first private homes in the United States equipped for central air conditioning