Currently considered to comprise six subspecies: Terrapene carolina carolina (Linnaeus, 1758), T. carolina bauri Taylor, 1895, T. carolina triunguis (Agassiz, 1857), T. carolina major (Agassiz, 1857), T. c. mexicana (Gray, 1849) and T. c. yucatana (Boulenger, 1895). The taxonomic status of the taxa yucatana and mexicana remains dynamic; they were treated as full species by Smith et al. (1996) and Stephens and Wiens (2003), but were treated as subspecies of carolina by Fritz and Havas (2007) and TTWG (2010). Butler et al. (2011) argued that the subspecies T. c. major is based on a phenotype resulting from introgression of genes of the extinct subspecies Terrapene c. putnami in eastern subspecies (mainly T. c. carolina) and does not warrant formal recognition.

A wide variety of population data sets at different sites and over different periods indicate a widespread persistent and ongoing gradual decline of Terrapene carolina that probably exceeds 30% over three generations, here conservatively considered as 50 years (possibly as long as 100 years). Causes of decline are not fully understood, but comprise a mixture of habitat destruction, pollution and pesticide effects, direct mortality from vehicle strikes, decreased recruitment through increased predation (particularly of eggs and juveniles) by subsidized predators (raccoons, foxes, possums, crows), intentional removal of animals for commercial pet trade (ceased), as personal pets or for 'turtle racing' (ongoing), and possibly disease and vegetational / forest succession trends in much of the eastern United States.

Terrapene carolina mexicana was considered as Least Concern on the grounds that it has a relatively wide range, and although there are modest threats from habitat degradation and collection, the subspecies is currently not thought to be significantly impacted by these. However, these threats should be monitored.

Terrapene carolina yucatana was considered Vulnerable because it is documented as rare with a total population estimated to be less than 10,000, it has a fairly small area of occurrence, and no subpopulation is estimated to contain more than 1,000 individuals; there is an ongoing decline in the number of individuals, due to ongoing habitat degradation and loss, and incidental take. Maximum reproductive potential in other box turtle subspecies is around 7-11 eggs/female/year, and maturity at five to eight years; values for yucatana may be lower because of its shorter active season. In the absence of quantitative data, the subspecies qualifies at least for Vulnerable A2bc, A4bc, B2ab(iii) and/or C2a(i).

Terrapene carolina occurs throughout North America south of the Great Lakes and east of the Rocky Mountains, from southern Ontario, Canada, south to the Florida Keys and Texas, as well as Northeastern Mexico and the Yucatan Peninsula (adapted from Iverson 1992, Dodd 2001).

Terrapene carolina carolina: Extreme southern Maine through Ontario, central Michigan and central Illinois to Georgia.
Terrapene carolina bauri: Peninsular Florida
Terrapene carolina major: southern Mississippi, southern Alabama, and western Florida
Terrapene carolina triunguis: Eastern Texas to southeastern Kansas, southern Missouri, and south-central Alabama.
Terrapene carolina mexicana: Northeastern Mexico, from Tamaulipas through eastern San Luis Potosi and Hidalgo to western Veracruz.
Terrapene carolina yucatana occurs in Campeche, Yucatan and Quintana Roo States of Mexico (Dodd 2001). Old records of occurrence in northern Belize are probably speculative, as no confirmed specimens are known from Belize.

Although widespread and historically common, populations of the various subspecies of the Eastern Box Turtle are perceived to be in gradual decline across the species' range, documented both at a number of sites where populations were monitored over decades, and from casual observations across much of the range. Reported population densities range from two to 24 animals per hectare of suitable habitat (Farrell et al. 2006, Ernst and Lovich 2009). 

Terrapene carolina mexicana apparently is localized in its occurrence, and relatively common where it occurs (Smith and Smith 1979, P. Lavin pers. comm. 2005).

Terrapene carolina yucatana is uncommon to rare: rural farmers interviewed by Buskirk (1993) said that some might see a half dozen animals per year, and none in another year. Only 18 localities have been recorded over a century of the species being known to science (Smith and Smith 1979, Buskirk 1993). While the similarly uncommonly collected Kinosternon creaseri proved widespread and abundant when specifically searched for, Terrapene yucatana was not found by any turtle surveys in Yucatan (Iverson 1988; Buskirk 1993, 1997; Artner 2004). Total population was estimated as most likely less than 10,000 individuals (J.C. Lee pers. comm. 2005)

Terrapene carolina occurs in a variety of habitats, including open broadleaf forests, field-forest edges, shrubby graslands, marshy meadows, stream valleys, palmetto thickets and other vegetation types. The species is omnivorous, feeding on mushrooms, plant stems, leaves, flowers and fruits, slugs, snails, earthworms and numerous other types of food. Box turtles disperse and facilitate germination of certain plant seeds.

Males reach 23.5 cm carapace length (CL), females 19.8 cm in subspecies major, other subspecies rarely exceed 16 cm CL. Maturity is reached at five to six years / 9-10 cm CL in males, and at seven to eight years / 9-10 cm CL in females of subspecies baurii. Longevity of 50-80 years is probably not unusual, but most animals do not surpass 25-35 years at present. Generation time is probably at the order of 35 years years (Kiester pers. comm. 2009). Reproducing females produce one or two clutches of three to five (range 1-11) eggs per year, but many females do not reproduce each year. Incubation takes about 73 (50-110) days. Hatchlings measure about 30 (27-36) mm (Dodd 2001, Farrell et al. 2006, Ernst and Lovich 2009).

Terrapene carolina mexicana lives mainly in tropical deciduous forest, rarely in mixed pine – deciduous forest or oak forest habitat at altitude (Dodd 2001, P. Lavin pers. comm. 2005). Most reported localities are below 500 m altitude (Smith and Smith 1979), but recoirds exist up to 900 m altitude in the Sierra de Tamaulipas (P. Lavin pers. comm. 2005). No specific information is available on food, feeding or reproduction (Dodd 2001).

Very little information available on the natural history of Terrapene carolina yucatana; preferred habitat apparently is low semi-xeric deciduous scrub forest broken by scattered grassland areas (Smith and Smith 1979); animals are occasionally encountered by rural farmers after slashing and burning of fallow fields before planting (Buskirk 1993). It is active only during the rainy season (June to early November) (Buskirk 1993). Largest recorded animal was 15.9 cm CL (Buskirk 1993), though Lee (1996) indicated up to 20 cm might be possible. Little or no information is available on food and feeding, reproduction, growth or maturity (Lee 1996, Dodd 2001).

A wide variety of factors impact Terrapene carolina, and the combination of impacts may leverage the severity of impacts. Degradation, fragmentation and destruction of Box Turtle habitat is widespread, from conversion of rural areas to suburban subdivisions and industrial areas, highways and other infrastructure, to consolidation of small-scale agriculture and timber plantations, and impacts of intentional or accidental vegetation fires, including prescribed burn regimes. Pollution and pesticide effects have been implicated in at least localized population declines, and this has impacted across much of the landscape.

Direct mortality from vehicle strikes, both as roadkill and from agricultural machinery, as well as fire mortality, reduces population density and recruitment potential. Decreased recruitment also results from increased predation, particularly of eggs and juveniles, by subsidized predators (i.e., unnaturally large populations of predators subsidized by easily available resources near human settlements) such as raccoons, foxes, possums, and crows, and possibly boar and dogs; introduced fire ants have also been implicated in Box Turtle population declines.

Intentional removal of large numbers of animals for the domestic and international pet trade has largely ceased, but incidental collection of animals as personal pets and for and 'turtle racing' continues, and amount to very large numbers over time. If returned to native habitat, released pet Box Turtles carry a risk of introducing disease into a native population, and animals from elsewhere represent the threat of genetic pollution. The role of disease in Box Turtle declines is not clear, but ear abscesses are particularly prevalent among Eastern Box Turtles and may indicate underlying stresses.

The overall impact of vegetational and forest succession occurring in much of the eastern United States is not clear, but anecdotal information suggests that while protected woodland areas develop into climax forests which are less suitable for Box Turtles, little new habitat is created or reverted to early successional stages. In certain areas (e.g., Egmont Key), Box Turtles rely on introduced vegetation species for shelter, and management measures to address invasive vegetation could adversely affect an area's suitability for box turtles.

The impact of climate change is not easy to predict, but recent mild winters in the Mid-Atlantic region have led to problems with animals emerging prematurely from hibernation, after which they are injured by subsequent cold periods (Dodd 2001, Farrell et al. 2006, Ernst and Lovich 2009.

Habitat loss (from sugarcane plantations, cattle grazing and fire impacts), collection for pet or subsistence consumption, and roadkills have all been recorded as threats to T. carolina mexicana. The species can tolerate low-level habitat changes, but probably not large-scale modifications. Habitat across much of the range is probably fairly stable at present, however this should be monitored.

Terrapene carolina yucatana: Some animals are killed by agricultural fires; charred animals encountered serendipitously may be consumed by rural farmers, but the species is too rare to go out looking for it.. Some animals are kept as pets locally. Very few animals are kept in captivity abroad (Buskirk 1993, Artner 2004). Road kill is also a problem for this rare, long lived species

Terrapene carolina experienced a pulse of exploitation for the international pet trade in the late 1980s and early 1990s, when the species was in demand after mass Mediterranean tortoise trade was curtailed by CITES; the genus Terrapene was itself included in CITES in 1994 after which exports ceased.
Box Turtles are in great demand for 'turtle races', and many animals are taken from from the wild, raced, and if returned, often to another location, leading to stress, increased likelihood of vehicle strike, disturbance to established animals, and possible transmission of disease.

Terrapene carolina is included in CITES Appendix II and is subject to a variety of State legislation and regulations in Canada and the United States. Turtles in general are protected from exploitation under Mexican wildlife and natural resource legislation; implementation is uneven.

The species occurs in a large number of protected areas, some of which are large and remote enough to buffer their resident Box Turtle populations from most impacts. A population of Terrapene carolina mexicana could occur in the Sierra del Abra Tanchipa Biosphere Reserve (217 km², cat. VI; core 167 km², cat. Ia), but no confirmation is available. Individuals and perhaps populations of Terrapene carolina yucatana could occur in a number of protected natural and archaeological sites, but this remains unconfirmed.

Obvious impacts on Box Turtle populations from residential, industrial, recreational and infrastructure developments should minimize impact on these turtle populations, through measures potentially including translocation, wildlife crossings, creation of replacement habitat, awareness, and other actions. Conservation measures for other species and habitat management focused on ecosystem maintenance or restoration must take the specific needs and sensitivities of Box Turtle populations into account, whether forest or fire management. Removal of Box Turtles from, and release of Box Turtles into natural populations should be minimized through appropriate enforcement of legislation and regulations, and through public awareness. Extensive research on status and conservation biology, and monitoring of population trends, is essential for sound conservation management of the species.

Population assessments, basic natural history studies, habitat monitoring, and confirmation of the occurrence of secure populations in protected areas, or establishment of one or more suitable PAs, are urgently needed for Terrapene carolina mexicana and Terrapene carolina yucatana.