<Tr> <Th> March 1, 1867 </Th> <Td> Nebraska Territory was admitted as the thirty - seventh state, Nebraska . </Td> <Td> </Td> </Tr> <Tr> <Th> July 1, 1867 </Th> <Td> Canada was formed from several British colonies, including New Brunswick, thus inheriting the dispute over Machias Seal Island and North Rock . </Td> <Td> Disputes: </Td> </Tr> <Tr> <Th> August 28, 1867 </Th> <Td> Midway Atoll was claimed . The largest island of Midway, Sand Island, had been claimed under the Guano Islands Act in 1858, but nothing more is known about this . </Td> <Td> Pacific Ocean: </Td> </Tr> <Tr> <Th> October 18, 1867 </Th> <Td> Alaska was purchased from the Russian Empire and designated the Department of Alaska . Due to a lack of quality surveying, the southeastern border with British holdings was unclear and disputed . </Td> <Td> Northwestern North America: </Td> </Tr>

Why did california and oregon become states before the other territories