in high school I saw a documentary about the evolution of the English
language, and in it was a whole segment on a very remote, quaint, and
quiet island off the coast of new england, on which 17th century
English was still spoken. The English was so old that subtitles had to
be used! What is the name of this island? I want to say "Tanjier" but
I don't think that's right.

Dear slurpie,

The island you have in mind is, without the slightest doubt, Tangier
Island off the coast of Virginia, only six miles from the Maryland
border in the Chesapeake Bay:

"At the present time there is still some evidence of the early English
that was spoken in 1607 [in the Chesapeake Bay area]. Features of this
Elizabethan English can be found on an isolated island of the
Chesapeake Bay. Tangier Island may be traveled to by ferry or by a
small airplane from mainland Crisfield. (...) Although the island is
one of the largest of the islands of the Chesapeake Bay, it is only
three miles long and one mile wide.  The local speech pattern has not
changed much since the island was first settled. ?Apart from their
geographical isolation, one of the reasons for the persistence of the
local speech pattern is that the islanders are tightly knit? (McCrum
91).  The current generation of the Tangier population is not showing
any signs of losing their unique way of speaking.  The perpetual
remoteness of the island will maintain the isolation of the language
and it is highly likely that the language will retain its
distinctiveness with the generations to come."
Source:
Diversity of a Conquering Language, by Sheri A. Armijo, University of New Mexico
http://www.unm.edu/~abqteach/linguistics/02-08-01.htm

"The Jamestown colonists came mainly from England's West Country and
spoke with the characteristic burr of these counties. This pattern can
still be heard in some of the communities of the Jamestown region,
especially Tangier Island in Chesapeake Bay. Because of the relative
isolation of this area, this "Tidewater" accent has changed only
slightly in 400 years and is sometimes said to be the closest we will
ever get to the sound of Shakespearean English."
Source:
NewScientist: Received pronunciation
http://www.newscientist.com/lastword/article.jsp?id=lw713

The educational documentary "American Tongues" features "Profiles of a
number of linguistic communities, including the remarkable relic area
of Tangier Island, Virginia". Maybe this is the documentary you
remember; here is a description, provided by the Center For New
American Media:
http://www.cnam.com/more_info/ameri3.html


Search terms used:
"tangier island"
://www.google.de/search?hl=de&q=%22tangier+island%22&btnG=Google-Suche&meta=
"tangier island" "old english"
://www.google.de/search?hl=de&newwindow=1&q=%22tangier+island%22+%22old+english%22&btnG=Suche&meta=
"tangier island" english
://www.google.de/search?q=%22tangier+island%22+english&hl=de&lr=&newwindow=1&start=0&sa=N
"tangier island" elizabethan linguistic
://www.google.de/search?hl=de&newwindow=1&q=%22tangier+island%22+elizabethan+linguistic&btnG=Suche&meta=
"tangier island" linguistic
://www.google.de/search?q=%22tangier+island%22+linguistic&hl=de&lr=&newwindow=1&start=0&sa=N


Hope this answers your question!
Regards,
Scriptor

Fantastic! Really fast, and amazing! Now I can sleep at night! I must
have searched the web for hours on my own with no success!