The Ray-Jefferson Mining Company was organized August 14, 1909, for the purpose of engaging in general mining. The first claims included, the "Ray" Lode, the "Jefferson" Lode and the "Lincoln" Lode, all in the Beaver Mining District in Shoshone County Idaho.

The first of the Ray-Jefferson directors included: David C. Smith, president; Daniel L. McGrath, vice president; E.G. Ellis, secretary/treasurer; A.G. Kerns, assistant secretary; and Edward Dolan.... Little action occurred under their direction until 1915, at which time the "Carlisle", "Hill Group," and "Carbon Creek" mining claims were purchased and parts of the Ray-Jefferson mine were leased to other mining companies.

In 1916, Eugene and Harry Day locked horns with Interstate-Callahan over the acquisition of the Ray-Jefferson property. Although they were successful in acquiring the property, a higher price was paid than the fair market value. The new directors included Eugene R. Day, president, secretary and treasurer; Harry L. Day, vice-president; George L. Garrett, D.L. McGrath and James J. Murphy. James P. Maggy took over the position of secretary/treasurer a year later. A number of loans were taken out for the construction of the Ray-Jefferson mill with the hopes of a large return on profits. However, the Ray-Jefferson failed to live up to the Days' earlier expectations and little profit was made.

In 1918 the mine was closed and in 1919 the company began yearly assessments to repay debts acquired during their two years of operation. The assessments were so regular that when no assessments were levied in 1932 and 1933, a number of concerned stockholders wrote to the company because they had not received their yearly notice of assessment and were worried about their stock becoming delinquent. Some stockholders even went as far as to send in money so the stock would not become delinquent.

By 1940, Eugene R. Day had passed away and a new set of directors took over. These included Jerome J. Day, president; George K. Garrett, vice president; S.F. Heitfield, secretary/treasurer; and Frank M. Rothrock. During this year, the Day brothers convinced the directors of the Ray-Jefferson, Blue Grouse, Virginia, and Amazon-Manhattan Mining companies, to consolidate their properties into one company. The Days felt the most economical way was to create a new company, the Monitor Mining Company, and then have each company in turn join Monitor, handing over all property owned by the companies.

The Ray-Jefferson Mining Company existed for twenty-six years in which time little profit was made. All three of the Day brothers were at one time or another on the board of directors with Jerome and Eugene Day playing a major role in the end of the Ray-Jefferson, as well as the beginning of the Monitor Mining Company.