<Tr> <Td> 1856--1864 </Td> <Td> 88% copper, 12% nickel (also known as NS - 12) </Td> <Td> 72 grains </Td> <Td> 4.67 </Td> </Tr> <Tr> <Td> 1864--1942 </Td> <Td> bronze (95% copper, 5% tin and zinc) </Td> <Td> 48 grains </Td> <Td> 3.11 </Td> </Tr> <Tr> <Td> 1943 </Td> <Td> zinc - coated steel (also known as 1943 steel cent) </Td> <Td> 42 grains </Td> <Td> 2.72 </Td> </Tr> <Tr> <Td> 1944--1946 </Td> <Td> brass (shell case copper) (95% copper, 5% zinc) </Td> <Td> 48 grains </Td> <Td> 3.11 </Td> </Tr>

When did they change pennies from copper to zinc