McAdams
The McAdams (MacAdam, McAdam) clan was a "sept" or subgroup of the larger MacGregor clan and probably used the tartans of the larger parent clan. Each Scottish clan used more than just one tartan. Different designs were used at different times for specific purposes.

MacGregor Septs
Black, Brewer, Caird, Comrie, Dochart, Gregor, Gregorson, Gregory, Greig, Grier, Grierson, King, Leckie, Lecky, MacAdam, Macara, Macaree, MacChoiter, MacConachie, Maccrowther, Macgrowther, Macgruder, Macgruther, MacLiver, MacNee, MacNeish, MacNie, MacNish, MacPeter, Malloch, Neish, Nish, Skinner

MacGregor History
The MacGregor’s motto “My blood is royal” is their claim to royal descent.  The clan was one of the most famous victims of the Clan Campbell’s expansionism. 

It held lands in Glenstrae, Glenlochy and Glenorchy. With the capture of Iain MacGregor in 1296, his property was passed to the Campbell Clan.  They were pushed further into Glenstrae. 

Historians generally agree that the "official" clan tartans were named and established around the end of the 1700s, but evidence show that they existed in a less official form long before that time. In fact there are records showing that they existed in a simpler form (woven, undyed sheep's wool) as far back as the third century A.D.

It is believed that most tartans were at first associated with the area they came from, rather than a specific clan. However, in those times many clans were inseparably linked to the area in which they lived, so the progression from geographical association to clan association is logical.

The most likely reason that specific tartans became popular in specific areas is that the local weaver (limited in his choice of dyes to what he could take from the surrounding areas) would produce large quantities of similar material out of convenience.

This fabric was often used to distinguish one clan from another in battle, and many references state that the chief had a large role in deciding the pattern and the colour of the plaids to be worn in battle. This tradition is carried on today in that all new tartans must must have the approval of the clan chief.