Suddenly said:
More importantly, these days off can be seen as negotiated for as part of the employment contract when one decides to work for the government, so it may be a wash in the end anyway...
IIRC (and it's quite possible that I don't), the MLK became a federal holiday right around the same time they refigured how federal salaries should be computed. When I started working for Uncle in 1975, your hourly rate was computed as the salary for your grade divided by 2,080, on the rationale that there were 2,080 hours in a work year (40 x 52). Your gross biweekly pay then was calculated as the hourly rate x 80. For example, if your grade paid a salary of $20,800/year, the hourly rate was $10.00, and your biweekly pay was $10.00 x 80 = $800.00.
Well, some beancounter noted that there were actually slightly more than 52 weeks in a year, 52-1/7, to be exact. So they adjusted the pay computation to divide your yearly rate by 2,087 hours, rather than 2,080. So your $20,800 yearly now became $9.97 per hour, and your biweekly pay became $9.97 x 80, or $797.60. You'd lose about $62.40 per year in pay as a result, the equivalent of a little less than a day's pay.
It was never actually said out loud that I recall, but I believe the MLK holiday was passed as part of a compromise that involved this very small pay cut. Give the GS'ers another holiday, but cut their pay by a sliver.