vitrified brick -- red, yellow and purple/black
By 1900, vitrified bricks had become the most common type of street pavement. A vitrified brick is fired at a higher temperature and for a longer period of time than a conventional brick used in construction or those used for sidewalks, making it harder and impervious to the absorption of water. Vitrified bricks were first used for paving in the United States in Charleston, West Virginia, in 1870. Hundreds of brick manufacturing companies appeared around the country, usually stamping or molding their company name and sometimes their location onto one face of the brick, which was oriented away from the surface and not visible upon installation. The high cost of shipping bricks limited their distribution and encouraged the emergence of brick manufacturing plants around the country or limiting their use in certain areas of the country. Ohio likely had more brick manufacturers than any other state. Columbus, Ohio, and St. Petersburg, Florida, have more surviving brick streets than any other cities in the country.