[bhaak]

1957 being the starting date is probably due to the used catalogs but remember that rockets have been launched decades before that.

Depending on your definition, at least the start of Goddard's rocket in 1926 or the A-4 that reached space in 1942 come to mind.

[nattybumppo]

Very true. 1957 is the starting point because the visualization only shows rockets that went to orbit (or that were intended to, at least); suborbital flights are not included.