Although a PhD in dance is rare in the US, historically the highest performance degree in dance (which includes choreography) has been a Master of Fine Arts (MFA) in dance. A few North American schools are, however, now offering an interdisciplinary PhD in dance.
Applicants must typically have an MA or MFA degree prior to applying for admission. Experience in one of the creative activities of theatre (acting, design, directing, dramaturgy, playwriting) will enhance chances of admission. The normal time to completion of a PhD in dance is 4 - 5 years.
Selected majors/areas of research for a PhD in Dance include

Dance Research

Cultural Studies in Dance -(humanistic and socio-cultural inquiry into dance

Dance Processes - performative, creative, healing, community building, and behavioral processes in dance, as well as scientific inquiry

Professional Applications - applied practice in particular educational settings/institutions and among specific populations, as well as arts advocacy
Students in a dance doctoral program must pass a written and oral qualifying exam and then complete and formally defend a doctoral dissertation based on original research. In general, all dance PhD programs require that successful candidates for the degree demonstrate:

The ability to conduct independent research at a high level, leading to completion of a dissertation which is defended before a committee of scholars. Because examinations given as part of a PhD curriculum assess expert knowledge, they are created and evaluated by a committee of experts, each of whom holds a PhD degree.

Proficiency in the tools necessary to carry out this research, including but not limited to computer skills, bibliographic competence, and reading of one or more foreign languages

Mastery of general and specific subject matter in the field of study before a committee of scholars.
Part- and full-time study options, along with various delivery modes - residential programs, distance education programs and online programs - are also available. North American PhD programs in dance welcome foreign students. However, fluency in spoken and written English is critically important.