Mason was probably already a practicing lawyer at the time of his marriage and was by 1824 a man of consequence in Alexandria.
The fight to get out of the District began in 1824, while it was not settled by Congress until 1846. The citizens of Alexandria, becoming tired of being in the District of Columbia, made an attempt to have Alexandria receded to Virginia. A meeting was held March 9, 1824, for the purpose of preparing a memorial to Congress on the subject. S. Thompson Mason was Chairman of the meeting....[8]
The memorial sent to Congress was couched in legal enough terms to have been drafted by Mason, who later became a judge. His political activities gave him enough local standing to insure his election as Mayor of Alexandria in 1827 and again in 1836.[9]
A glimpse of Mason as a family man can be seen in a reply to a letter from his wife in which she complained of an exchange of words with Huntley's overseer (in 1828), Slighter Smith. Mason, who must have been in court at Leesburg, wrote:
I have been indeed a little surprised at hearing the conduct of Mr. Smith. Altho' I knew about the general unkind and bad temper which he possessed, I had no idea that he would have ventured to exhibit it in your presence—or have him guilty of the insolence of threatening violence in your presence and to one under your protection.... I still cannot believe that he would seriously attempt it....
In that same letter Mason noted:
... the great pleasure and pride I have ever felt in seeing you placed above the flame, and having you so looked up to by others.[10]
As a good plantation manager, he also included a note to Smith informing him of his surprise and displeasure at the outbreak and suggesting:
I feel it is proper to inform you that I shall feel it my duty to inquire strictly into this subject—And with regard to the threatened violence I beg leave ... to put you on your guard and to inform you that any new attempt will be followed by the most serious consequences.
Mason lived in several houses in Alexandria (see Appendix A), but it was the time he spent at Colross which seems to have received the most notice. Mrs. Marian Gouverneur wrote in her book, As I Remember: