How are San Antonio and Cincinnati worthy of top 20 when there are so many other good zoos?? If they are worthy of being in a top 20 then there is a definitely a shortage of good zoos in the country.
Woodland Park is clearly missing from the list with the excellent Northern Trail, Brilliant Tropical RainForest section with Jaguar cove and one of the best gorilla exhibits in the country, also Tropical Asia with the elephants and tapirs, and finally the awesome African Savanna.
I've been to San Antonio once so I can't defend it but--while Cincinnati would be in a personal top ten--I think it earns a 11-15 place spot on many lists of this type for the following reasons:
*Family geared. Large amount of amenities for visitors. If you want to find a US zoo that would be just as good for children, look no further. Bronx doesn't provide the amount of visitor enrichment Cincinnati does.
*Sumatran rhinos. Top breeder of the species. Oh yeah, a great SHADED exhibit for them too.
*Only real insect house in the US. And a good one at that (complete with children friendly education games)
*Jungle Trails; good breeding programs for primates in general...one of the largest holders of both bonobos and gorillas in the states.
*Sea Eagle and Condor exhibits are superb.
*One of the few institutions not in Florida to hold manatees.
*Good gorilla families and lines (though they now are no longer allowed to breed...)
*Cheetah breeding programs and the work they have done (and plan to) for endangered tiny cats. Expanded cheetah run exhibit. One of the best collections (I did not say exhibits, mind you) of smaller cats. One of the few institutions to hold fossas.
*It's also a botanical garden--not just a zoo. One of two acreditted botanical gardens in the state and one of the largest collections of fauna and flora on this side of the country. P&G Botanical Garden building.
*History. Some of the oldest zoo buildings in the country.
Sure, the elephant, girafee, gorilla, and bird exhibits are average. And I will never attempt to justify the reptile house or the size of some enclosures in the cat house but it still deserves a top 15 or 20 spot. I think sometimes we all hold zoos at higher standards because we've seen the top top zoos but when it comes down to it, not everyone goes to a zoo to rate the square footage of every exhibit or the type of substrate used. Many go to a zoo for pure enjoyment and Cincinnati provides that (as does San Antonio, trifold).
What other zoos are SO much more deserving of a top 20 spot than either? I think it's really easy to argue the top 10 because there are a cluster of zoos that belong in there or out of there depending on whose making the list but when you get into the 15-20 range, I think it's another story.