Robert McMaster was born about 1740 most likely in Ireland, probably North Ireland.  His parents are unknown.  He first appears in Cecil County Maryland records  in the List of Taxables of Octorara Hundred 1766, page 82 from Inhabitants of Cecil Ct. MD 1649-1774 by Peden.  After his name is (Beal). I do not know what it means. Then he is listed 1779 as part of Petition of Tenants of Susquehana Manor. page 41,   These areas are in the northwest part of the county.

Peden also noted even earlier McMasters in Cecil County,  John McMaster in 1740, and Barnet McMasters in 1752.   I do not know of any connection to our family, but certainly it is possible.Then there are suggestive items found in Buried Genealogical Data by Kenneth Scott.  It contains lists of letters left in Post Offices in or near Philadephia.  There were two letters in paper addressed to Robert McMaster in Nottingham.  One dated Aug 9, 1759, the other Jan. 3 1760.

So I can envisioned a young man leaving his Scottish home and anxious parents sending letters that never arrived.  It is the right place, but i cannot confirm that it is our Robert.  The first documented sign of him being in Cecil county is  on Jan 19, 1773 Robert McMaster purchased a mare and a colt from Samuel Cresswell.  Cecil county Deed, vol 13, page 111.

Robert McMaster wed Margaret Murphy maybe 1768-70, and we are guessing here. but it is believed that she was his only wife and bore all his children.  Gary Burns The McMasters of Cecil county.   There is documentation as of 1793.  From Cecil County Will Abstracts by John McCoy # 206 is the will of John Murphy, page 347 in will book, written on Sept 15, 1793. In the will John Murphy names his daughter Margret McMaster - wife of Robert McMaster and Robert is named one of the two executors.  a witness was Samuel McMasters, probably son of Robert and Margaret.

According to Mr. Burns, Robert and Margaret had the following children.  He places them in this order,  If I differed I explained why
1. Mary McMaster she wed David Archibald in 1790.
2. Jane McMaster she wed John Fisher in 1794.
3. Sarah, "Sally" McMaster never married. 
4. Robert McMaster born in 1782, he wed Martha W. Taggart in 1822, he died March 4, 1849 at age 67 years, 11 months and 20 days. The date and age are given on his tomb at Nottingham        Cemetery.  Find a Grave.  So the math says he was born March 15, 1781.
5. Samuel McMaster Mr. Burns has him after 1782, however, if he did indeed witness the will of John Murphy in 1793, he would have been older than 11 years.  I would put him closer to 1775 and probably the oldest son. and if he were >16 in 1790 probably 1772 - 1774.   He died in 1821.
6. Keziah McMaster wed Thomas Fisher in 1821
7. Andrew McMaster  wed Ann Dobbin about 1813.  She died after 1820. Andrew remarried about 1826 to widow Margaret Watson. He died in 1849.
8.  Rebecca McMaster, it is believed she died fairly young.

The only birthdate actually known is that of Robert Jr. who has age listed on his tombstone.  The others are all speculation. 

Robert McMaster is listed Intendants Ledger B, folio 134 on June 15, 1785.  This from the Maryland Archives Revolution War Records.  I don't know what the Intendarts were ????

In 1785 Robert McMaster patented property in Susquehanna Manor.  It was just over 210 acres and was named McMaster's Delight.  A brick home was built on the land between 1785 and 1802.  It is  still standing and being lived in.  From The Nottingham Lots: A Tercentenary Celebration 2001 by the East Nottingham Trustees.   However, there is a document created for the McMaster Nesbitt House on the Maryland Historical Trust Inventory for State Historic Sites.  This says the house was built about 1830-1840,  It is on Waibel Road west of Battle Swamp.  Battle Swamp is now called Woodlawn.  The house which sits on the bank of Basin Run Creek just next to a bridge that was out of service for a while.. The original structure is brick now painted yellow with a large wood 2-story addition behind.  The McMaster family lived there for many generations.  Pat. Cert. #636.

Census Cecil County North Susquehanna Hundred 1790 has the family listed: the names given are my guesses and they truly are just guesses except for the 2 Roberts.
Robert McMaster
3 males > 16 
2 males < 16
8 females     
no slaves

The 1810 Cecil County Census page 62, Northern Township (I've not found 1800.
 Robert McMaster                      
1 male < 10
1 male 16-25                     2 females 16- 25
3 males 26-45                    1 female 26-45
1 male > 45     Robert        1 female >45        Margaret

 I cannot put in names, but I believe it very likely that in both census grown children were living with Robert and Margaret with their families.

In 1793 Robert and Margaret McMaster signed the Oath of Allegiance, becoming Naturalized Citizens on Feb. 1793.  It stated Robert's birthplace was Ireland, Margaret was not given.It also stated they lived in Battleswamp, Maryland.

The will of Robert McMaster was written April 4, 1812  Cecil County Clerk of Wills, will book GG 7, page 131.  I only saw one page, but believe there is more.  Robert named:
wife,  Margaret
son, Samuel to get 1/2 plantation
son Robert to get the other half.   when Samuel died in 1821, his heirs were his siblings and they sold the plantation to Robert jr.
son Andrew $200 to get in 4 payments of $50.
daughter  Mary Archibald $1
daugther Jean Fisher was named without any designation that I found on the one page
daughters Sarah & Rebecca McMaster - 10 pounds sheep (money??) each
   there may be more, but I don't have it.

Robert McMaster died March 16, 1816.   I do not know where he is buried.  I do not know when Margaret died.