| 1937 |
 The Child Development Laboratory, operated by the Hogg Foundation and the American Association of University Women of Tyler, began in the home of Mr. D.K. Caldwell. Later the CDL spread to a remodeled garage, additional buildings and a large area behind the Caldwell home.
Parrots, monkeys, squirrels and other animals were added to the playschool for the children's enjoyment. |
| 1953 |
 Animals from the playschool were moved to the current zoo site.
Mr. and Mrs. D. K. Caldwell opened the Caldwell Children's Zoo. |
| 1967 |
 Caldwell Zoo housed 500 animals from 87 species.
Brigham the Lion, a retired television star, came to live at Caldwell Zoo. Another animal star was added when Bobby the chimpanzee arrived at the zoo. |
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Trespassers broke into the zoo and killed several small animals and vandalized the property. |
1971
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 After the tragic vandalism of the zoo in 1970, area children collected pennies to help restore the zoo. With the money collected, Mr. and Mrs. D.K. Caldwell purchased Kimbo, an Asian elephant Kimbo arrived at Caldwell Zoo from Bangkok, Thailand, in March. She was six months old and stood 36 inches tall. Kimbo became the driving force behind the creation of a modern, state-of-the-art zoo.
Sobi, the Bengal tiger, was added to the zoo's exotic and endangered animal collection. |
| 1972 |
 The American Association of Zoological Parks and Aquariums AAZPA (now the American Zoo and Aquarium Association, AZA) was incorporated as the membership organization for zoos and aquariums.
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| 1976 |
 The Tyler City Council granted a permit for increasing the eight-acre zoo site to about 40 acres.
A new masterplan was completed for the Caldwell Zoo. |
| 1977 |
 Mr. D.K. Caldwell died.
A new elephant facility (the current rhino building) was opened and housed Kimbo and a new African elephant, Rolinda. |
| 1978 |
 The giraffe barn was built and three giraffes came to the zoo—Aisha, Nyika and Suzi.
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| 1980 |
 A new entrance complex, lemur island and flamingo pool were completed.
The Education Department was established and staff conducted classes in the classrooms at the entrance complex. |
| 1982 |
First baby giraffe born.
Chip, a male African elephant, arrived at the zoo. |
| 1983 |
A 15-acre Native Texas and Texas Farm expansion was opened. |
| 1984 |
The Texas reptile and aquarium building was opened. |
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1987 |
The zoo completed the Phase I and II of the East Africa section, adding a hoofstock barn and African plains, a modern elephant house designed to hold African elephants, the Overlook plaza, a cheetah facility and rhinoceros facility which was remodeled from the old elephant barn |
| 1989 |
The first Chilean flamingo chick was hatched. |
| 1990 |
The commissary (animal food preparation area) and purchasing department building was completed. |
| 1991 |
Phase III of East Africa was completed. This area includes blue monkeys, black-backed jackals, African lions, bongo, Colobus monkeys, leopards and a large aquarium building.
 Sheena, the jaguar, was born at Caldwell Zoo.
Caldwell Zoo, in collaboration with other zoological institutions, produced the first cheetah through artificial insemination techniques. |
| 1992 |
The zoo administration and maintenance building was completed.
The American Association of Zoos and Aquariums (AZA) awarded the Caldwell Zoo an exhibit award for Phase III of the East Africa project. |
| 1993 |
A garage shop was opened.
The zoo welcomed Ebony, the first black rhinoceros born at the Caldwell Zoo. |
| 1999 |
Mrs. Lottie Caldwell died. |
| 2001 |
 The zoo welcomed its 22nd baby giraffe, Ethyl, on January 31st.
The 128th flamingo chick was hatched.
The 7th giant anteater baby was born. |
| 2002 |
 Construction was completed on a new, expanded veterinary hospital, brooder house, quarantine facility and off-exhibit animal holding space.
Visitor and bus parking lots were expanded. New restroom and picnic facilities were added to the bus parking area.
The Caldwell Zoo began an intensive breeding program for Attwater's prairie chickens. Five chicks were successfully raised the first year.
Construction began on a new entry complex, expanded lemur island and flamingo pool. |
| 2003 |
Construction completed on new entry. |
| 2004 |
Warthogs and wildebeests came to the zoo's African savannah. |
