To your point on raising the minimum wage and likely causes, you listed “reducing employee turnover” as one possibility and followed that up with “Henry Ford did it” and “Costco does it”.

I occurs to me that these two examples are at best self-refuting against the cause for raising the minimum wage, and at the least, questionable examples to use to support the much broader question of the affect on employment as it relates to all businesses that are subject to minimum wage standards. Here’s why:

1) Ford and Costco are just two examples (there are numerous others too) showing that the market does recognize when higher wages are warranted. In the end, their higher wage offerings didn’t require gov’t action for it to occur.
2) Ford paid his workers who were heads of households and in many cases, in their chosen career. It seems a bit disingenuous to me to try and draw a meaningful parallel between those jobs and many (granted, not all) minimum wage jobs that are filled often times by high school kids looking to work a few hours at a fast food joint to make some extra money.
3) Finally, if/when the gov’t artificially equalize the playing field (i.e.…and thus Costco’s competitors end up being forced to pay same wages), they’ve in a sense cut down Costco’s competitive employment advantage and given their employees less reason to stay since the big box store down the street is now paying same/similar wages).

Bottom-line: In seems to me, at least on this one point(given the two examples you cited), it supports the argument that a federal mandate is NOT required as the market will make adjustments and individual companies will be justly rewarded in doing so due to higher employee retention. In the very least, it seems to only support the correlation seen when specific individual companies voluntarily offer higher wages. This is a completely different question than the more broad/sweeping one. That is, “why doesn’t an increase in the minimum wage seem to affect employment?” Maybe it doesn’t, but in my opinion, neither the Ford or Costco examples would appear to be relevant in answering this question.

Is there any research that details how many minimum wage employees also have to receive government assistance? And, how is unemployment in Washington and Oregon that have a high minimum wage?

1—Employers would have to adjust their pay scales to move up those currently making $9 to $10 to $11, so that would mean somebody who makes $15/hour now may end up making a bit more depending on the pay scale adjustment. This is the White House’s view. They refer to the boost in wages for those making above the $7.25-$9 range a ‘ripple effect’.

2—Employers decide to hold pay scales constant or reduce pay raises/bonuses for those making above $9 hour –‘wage compression’- as their labor costs increase. A recent academic study did find evidence of wage compression resulting from a minimum wage increase in Georgia and Alabama.

3- Firms will pass on the cost of increased wages to the consumer. One literature review cited by Wonkblog found that a 10% increase in minimum wage led to 4% increase in prices (That is not a 1 to 1 relationship.)