Andorra Nursery was one of the major nurseries in the US, and it was situated in Philadelphia, at the northwestern end of Fairmount Park along the Wissahickon, and extending into Montgomery County, as well.
Starting in the 19th century and extending up to 1961, they grew and sold thousands upon thousands of plants there – and its history is still readily visible if you go there now. There are Japanese maples in plantation rows right near Northwestern Avenue; there are European beeches towering over the canopy; there are clusters of holly, and evodia, and cedrela. Walking through the forest that has grown up and around it, you can still the nursery that once was.
A comprehensive history of the nursery was written in 1974, by John Swartley (and published in the Bulletin of the Morris Arboretum), and Janet Evans, librarian at PHS, has posted a pdf of it here: http://pennhort.libanswers.com/a.php?qid=1271749