<Tr> <Td> 1910 </Td> <Td> 37,200 </Td> <Td> 2,100 </Td> <Td> 440 </Td> </Tr> <Tr> <Td> 1930 </Td> <Td> 122,500 </Td> <Td> 15,000 </Td> <Td> 2,300 </Td> </Tr> <Tr> <Td> 1950 </Td> <Td> 432,000 </Td> <Td> 58,200 </Td> <Td> 6,600 </Td> </Tr> <Tr> <Td> 1970 </Td> <Td> 827,000 </Td> <Td> 208,000 </Td> <Td> 29,900 </Td> </Tr>

The growth of sports institutions in the us during the 19th century was closely related to