Context: Roads in the US have been paved with materials that include asphalt/bitumen since at least 1870, when a street in front of the Newark, NJ City Hall was paved. In many cases, these early pavings were made from naturally occurring "bituminous rock", such as at Ritchie Mines in Macfarlan in Ritchie County, West Virginia from 1852 to 1873. In 1876, asphalt-based paving was used to pave Pennsylvania Avenue in Washington, DC, in time for the celebration of the national centennial. Asphalt/bitumen was also used for flooring, paving and waterproofing of baths and swimming pools during the early 20th century, following similar trends in Europe.

Question: Since what date has asphalt been used for road paving in the US?
Answer: 1870

Question: In front of what NJ building was the street paved with asphalt in 1870?
Answer: City Hall

Question: What natural substance was used in early road pavings?
Answer: bituminous rock

Question: From what Virginia  mines was asphalt obtained for early street pavings?
Answer: Ritchie Mines

Question: For what purpose was asphalt used in swimming pools and baths?
Answer: waterproofing

Question: Ever since 1773, roads in the United States have been paved with what?
Answer: Unanswerable

Question: What have been paved with asphalt since at least 1920?
Answer: Unanswerable

Question: What was Ritchie Mines used to waterproof during the 20th century?
Answer: Unanswerable

Question: When was New York's, Pennsylvania Avenue paved?
Answer: Unanswerable

Question: What was NJ City Hall used for during the early 20th century?
Answer: Unanswerable