As labor was the chief occupation of the pioneer, and in the noble army of workers Judge Mercer has been arrayed throughout his life, he was a bright, active boy, quick in mathematics and mechanical work.

In 1830 young Mercer started a store in a little, old log cabin in Princeton, pursuing this enterprise for a year, before abandoning it because of the close confinement it entailed.

He then continued farming up to 1851, when he sold out, settled up his affairs, and in April 1852, with his wife and four children, left his Illinois home, and with horse teams crossed the plains to Oregon.

On this trip, Mrs. Mercer fell ill in The Dalles and died in the Cascade Range, leaving a bereaved husband and four small children, the eldest being not quite 14.

The following winter was passed in Salem, where Mercer purchased one-half interest in a blacksmith shop and worked from 6 a.m. to 11 p.m. Flour was $40 per barrel and all other provisions in proportion.

His claim being situated back from the water, the young men turned out and assisted in cutting a trail wide enough for his wagon to pass through to his ranch, and for a number of years he did the teaming for the town.

With the organization of King County in 1854, Mercer was appointed one of the first commissioners, and in 1858 he was elected probate judge and held the position for ten consecutive years.