Here tells us that "thou" is restricted to:
It is used in parts of Northern England and by Scots.... In the 17th century, thou fell into disuse in the standard language but persisted, sometimes in altered form, in regional dialects of England and Scotland
It remains, what are these regions? I did a wee bit o' research, and came up with:
thew : you
In south Lancashire...where older people,...will still use the pronoun "tha" or "t'" (thou) and "thi" (thee) instead of "you" as the 2nd person singular personal pronoun, subject and non-subject form respectively; "thy" as the 2nd person singular possessive adjective instead of "your"; and "thine" as a second person singular possessive pronoun instead of "yours"
This is Lancashire below:
Use of the singular second-person pronoun thou (often written tha) and thee.
This is Yorkshire below:
Up until the mid 20th century it was not uncommon to hear the use of informal forms of address, Thee and Thou
This is East Midlands below:
The traditional Black Country(English West Midlands) dialect preserves many archaic traits of Early Modern English and even Middle English, and can be very confusing for outsiders. Thee, Thy and Thou are still in use,
This is English West Midlands below:
Black Country is to the north and west of Birmingham, and to the south and east of Wolverhampton.
Potteries dialect(Spoken by north Staffordshire):
noticeable features of the dialect....and the use of thee and they in place of you
This is Staffordshire below, and remember, only north Staffordshire speaks Potteries:
Yorkshire, Lancashire, and Cumbrian are all in northern English, and the northernmost parts of it speak nearly identically with Scots, who also use "ye", and "thee".
Hope that helps!