A machine to cool, dehumidify and circulate air was invented in 1902 by Willis Carrier of Brooklyn. Its impact expanded with compressors in the 1930s and window units in the 1950s. Yet while these technological advances slowly became global, their impact on American society remains crucial. After the Second World War, air conditioning facilitated life in humid regions like the South and South-west for new immigrants and regularized production and services (the earliest uses of air-conditioning in the South were in industry). Beyond this nascent Sunbelt, year-round climate control also changed architecture, although risking the “sick building syndrome” in which diseases are recirculated through an air system. It has also altered relations with the environment, especially as life has become encapsulated in air-conditioned homes (or rooms), cars and offices: New Urbanism, for example, re-establishes the porch and street interactions in opposition to this technological climate.