There were just over 200 McGarveys listed in the 1857 Griffith Valuation - which means that about one in 5000 Irishmen in the 1850's was a McGarvey. Half of these 200 McGarveys are listed in the Valuation as located in County Donegal. Some histories state that the McGarveys actually originated in Co Tyrone. Griffith Valuation shows three widely scattered townlands in Co Tyrone with sizable groups of McGarveys. These were Glenchiel townland in Upper Bodoney parish, Gallan Upper townland in Ardsmore parish, and Lurganboy townland in Errigal Keerogue parish. There were also McGarveys in the southeast corner of County Derry. The Garvey/McGarvey DNA Study has found that the Co Tyrone/Derry McGarveys may have a different genetic signature than the Co Donegal McGarveys. .
The McGarveys in Co Donegal were found in two main groups (shown by the blue circles on the map above). The blue circle on the left is the McGarveys of Gweedore parish, and the blue circle in the middle of the county is the McGarveys who attended the RC church in Creeslough. Both these regions are surprisingly small by today's standards - just a couple of miles by a couple of miles. So these areas were more the size of what we would think of as neighborhoods today. The Gweedore group of McGarveys was found along a few mile strip of coastland in the civil parish of Tullaghobegley - which includes a hill named Carrickmacgarvey (shown in the Google map below).
Viewing the Larger Map version shows that a few mile drive along R257 would bring one through many of the townlands in which McGarveys were mentioned in the Tullaghobegley Parish Griffith Valuation. There were also McGarveys just across the border into the civil parish of Templecrone in the townlands of Rinnafarset and Loughanure.
Viewing the Larger Map version shows the "neighborhood" of the Creeslough McGarveys stretching from the townlands of Glenineeny, Gleneraugh, and Glenieragh to another group of McGarveys just to the southeast in the townlands of Carrownagnonagh and Golan.
Modern distribution surveys based on Irish telephone listings indicates that there may have been a migration away from the distribution shown in the Griffith Valuation of 1857.
The Garvey/McGarvey DNA Study has found genetic signatures for the McGarveys that are distinct from the rest of the Garveys. It has also found that McGarveys have tended to retain the "Mc" prefix to the name (only one out of 18 Garveys has been found to really be a McGarvey).
In the mid-1800s the majority of the McGarveys in the US were living in the states of New York, Ohio , Massachusetts, and Pennsylvania. These maps show where in each of those states the McGarveys resided. Each blue circle indicates a place where a McGarvey lived in the year of the census.
The links below are maps of each county that show the civil parishes in which McGarveys held land.