The following data is extracted from History of the Pacific Northwest, Oregon and Washington, 1889.
THOMAS MERCER. - This well-known and highly respected resident of Seattle, Washington, whose portrait, together with a view of his beautiful home, is appropriately placed in this volume, was born in Harrison county, Ohio, March 11, 1813, and was the eldest son of Aaron and Jane Dickerson Mercer, - the latter a native of Pennsylvania and the former from an old Virginia family. Thomas resided at his birthplace until twenty-one years of age, and after his school days entered his father's woolen factory and learned the trade thoroughly. In 1834 he moved with his parents to Bureau county, Illinois, and located on a farm near Princeton.
April 20, 1852, with his wife and four children, he left the Illinois home, and with horse-teams crossed the plains to Oregon, being captain of the Mercer train. On arriving at the Cascades, Oregon, he buried his wife, who had been stricken with disease at The Dalles. His first winter in Oregon was passed at Salem; and in the spring of 1853, with one of his companions of the plains, Mr. Dextor Horton, now a well-known banker of Seattle, he came to the present site of that city. He took up a claim of one hundred and sixty acres adjoining that of D.T. Denny, - now having all undergone the wonderful transformation from a tract of wooded, rugged hillside to lots graded and covered by buildings.
On coming to the Sound, Mr. Mercer brought with him the same team of horses with which he had crossed the plains, - the first that ever reached the neighborhood of Seattle. He built in 1854, upon his claim, a residence that is still standing, and in contrast with the beautiful home in which he now lives is a striking evidence of the prosperity of its owner as well as of the city. A few years ago he laid out his entire farm in city lots, and realized a fortune from their sale. He deserves mention also as the one who first christened the beautiful lakes which are the pride of Seattle, having in an address delivered at a picnic in1855 suggested that they be called Union and Washington.
In June, 1858, he was elected probate judge of King county, a position that he held for ten years, declining thereafter a re-nomination. He was also one of the first county commissioners of that county. In 1883 he built his present residence, where he now enjoys the fruits of a well-spent and prosperous life.
Mr. Mercer was married in 1859 near Salem to his present wife, Miss Hester Ward, a native of Kentucky. Two of the four children who came across the plains are now living near the old homestead in Seattle, the third and eldest living near Olympia.
Source: History of the Pacific Northwest, Oregon and Washington, 1889