Manhole covers by year

Until 1925 (the dates we have)

• 
  1851 (Madrid, Spain)
• 
  1874 (Vienna, Austria)
• 
  1881 (Rome, Italy)
• 
  1883 (Valladolid, Spain)
• 
  1889 (Toronto, Canada)

• 
  1890 (Minsk, Belarus)
• 
  1897 (Rome, Italy)
• 
  1900 (Elektrostal, Russia)
• 
  1901 (Valladolid, Spain)
• 
  1902 (Elektrostal, Russia)

• 
  1904 (Ontario, Canada)
• 
  1907 (Valladolid, Spain)
• 
  1912 (Somewhere in the USA)
• 
  1914 (Salamanca, Spain)
• 
  1915 (Valladolid, Spain)

• 
  1916 (Pisa, Italy)
• 
  1921 (Southampton, England)
• 
  1922 (Rome, Italy)
• 
  1924 (Valladolid, Spain)
• 
  1925 (Luhansk, Ukraine)

1926 - 1950

• 
  1926 (València, Spain)
• 
  1927 (Heilbronn, Germany)
• 
  1928 (Tübingen, Germany)
• 
  1929 (València, Spain)
• 
  1930 (Sueca, Spain)

• 
  1931 (Teruel, Spain)
• 
  1932 (Moscow, Russia)
• 
  1933 (Ourense, Spain)
• 
  1934 (Sueca, Spain)
• 
  1935 (Gandia, Spain)

• 
  1936 (Vic, Spain)
• 
  1937 (Ourense, Spain)
• 
  1938 (Ourense, Spain)
• 
  1939 (Requena, Spain)
• 
  1940 (Rome, Italy)

• 
  1941 (Quito, Ecuador)
• 
  1942 (Salamanca, Spain)
• 
  1943 (Orihuela del Tremedal, Spain)
• 
  1944
• 
  1945 (Cullera, Spain)

• 
  1946 (Potes, Spain)
• 
  1947 (València, Spain)
• 
  1948 (Peñaranda de Bracamonte, Spain)
• 
  1949 (Alginet, Spain)
• 
  1950 (Quito, Ecuador)

1951 - 1975

• 
  1951 (Cheste, Spain)
• 
  1952 (Segorbe, Spain)
• 
  1953 (Alcántara, Cáceres, Spain)
• 
  1954 (Massalfassar, Spain)
• 
  1955 (Catania, Italy)

• 
  1956 (Tordesillas, Spain)
• 
  1957 (L'Alcúdia de Crespins, Spain)
• 
  1958 (Philadelphia, USA)
• 
  1959 (Mosqueruela, Spain)
• 
  1960 (London, Canada)

• 
  1961 (Casas Ibáñez, Spain)
• 
  1962 (Villar del Arzobispo, Spain)
• 
  1963 (Horcajo de Santiago, Spain)
• 
  1964 (Sochi, Russia)
• 
  1965 (Almenara, Spain)

• 
  1966 (Navalvillar de Ibor, Spain)
• 
  1967 (Castalla, Spain)
• 
  1968 (Rostov-on-Don, Russia)
• 
  1969 (Aranjuez, Spain)
• 
  1970 (Tallinn, Estonia)

• 
  1971 (La Cuba, Spain)
• 
  1972 (Becedas, Spain)
• 
  1973 (Massalfassar, Spain)
• 
  1974 (Gelendzhik, Russia)
• 
  1975 (Medinaceli, Spain)

1976 - 2000

• 
  1976 (Narrillos del Rebollar, Spain)
• 
  1977 (Ribota, Spain)
• 
  1978 (Kherson, Ukraine)
• 
  1979 (Armuña de Almanzora, Spain)
• 
  1980 (Villa del Rey, Spain)

• 
  1981 (Elektrostal, Russia)
• 
  1982 (Godelleta, Spain)
• 
  1983 (Athens, Greece)
• 
  1984 (Riga, Latvia)
• 
  1985 (Almussafes, Spain)

• 
  1986 (Benassal, Spain)
• 
  1987 (Rome, Italy)
• 
  1988 (Cullera, Spain)
• 
  1989 (Zaragoza, Spain)
• 
  1990 (Bergen, Norway)

• 
  1991 (València, Spain)
• 
  1992 (València, Spain)
• 
  1993 (València, Spain)
• 
  1994 (Meliana, Spain)
• 
  1995 (Quito, Ecuador)

• 
  1996 (Cape Town, South Africa)
• 
  1997 (Tel Aviv, Israel)
• 
  1998 (Nafplion, Greece)
• 
  1999 (València, Spain)
• 
  2000 (Eilat, Israel)

2001 - ....

• 
  2001 (Ottawa, Canada)
• 
  2002 (Wellington, New Zealand)
• 
  2003 (Wrocław, Poland)
• 
  2004 (Vienna, Austria)
• 
  2005 (Groningen, the Netherlands)

• 
  2006 (Albuquerque, USA)
• 
  2007 (Istambul, Turkey)
• 
  2008 (Tulsa, USA)
• 
  2009 (Łódź, Poland)
• 
  2010 (Acre, Israel)

• 
  2011 (Karaganda, Kazakhstan)
• 
  2012 (Shkodra, Albania)
• 
  2013 (Oude Pekela, the Netherlands)
• 
  2014 (Mezcala, Mexico)
• 
  2015 (Tbilisi, Georgia)

• 
  2016 (Vaughan, Canada)
• 
  2017 (Lublin, Poland)
• 
  2018 (Groningen, the Netherlands)
• 
  2019 (Sárospatak, Hungary)
• 
  2020 (València, Spain)

• 
  2021 (València, Spain)
• 
  2022 (València, Spain)
• 
  2023 (València, Spain)
• 
  2024 (València, Spain)