Slavery is always imposed or facilitated by government, but it has come in a variety of flavors.
During WW2 the German government enslaved French, Jewish and other prisoners to work in factories usually owned and operated by companies under contract to supply munitions. Those familiar with Schindler's List may recall how he paid the SS two marks a day per worker, but the workers saw none of it.
In the antebellum South, the US government obliged every state to capture and return any slaves who escaped, and denied all slaves any access to its court monopoly; so although plantation owners employed the slaves it, too, was possible only because government made it so.
It's worth comparing that pre-1865 enslavement to our status today. Let's look at labor and reward, then at the less measurable aspects of enslavement.
Labor, first, was then taken in total. 100% of the slave's work was confiscated by the Master (he was never a true "owner", because he's knowingly purchased a self-owning person who had been kidnapped or stolen) and no wage was paid. In the first half of the 19th Century about 18% of the population were slaves, so it could be said that society was 18% enslaved.
It's a bit more than that, though, because a small part of the fruits of the labor of non-slaves was also confiscated, by government; the total grab was about 6%, at all its three levels. (That rose to 9% by the Century's end.) So 82% were enslaved for 6% of their working lives, hence the total level of enslavement was (100 x 18) + (6 x 82) = 23%.
Today, everybody's labor is taxed at a total rate of about 50%, so our society as a whole is more enslaved than America was prior to 1861, by a factor of (50/23 =) 2.17.
Of course, that's not to say blacks ought to be re-enslaved! Rather, the need is for nobody to suffer any enslavement. As in the coming zero government society.
Rewards, however, need also to be measured and compared, to the extent possible. Black slaves were rewarded not with cash, but with housing, food, water, clothing and medical care - all free. The standard was low, but the Master in his own interests provided sufficient to keep them healthy and strong. He regarded them as his own property, and wanted to get the most out of them, so he maintained them adequately. Were he to deprive them, he would lose.
Today, our masters in government do not provide any of those five necessities, except medical care for the old and young. Further, ominously and unlike the slave holder, there is no particular advantage to government in having a strong, healthy population; it needs a work force and a productive segment, but if a noticeable minority die or fall ill, its nose loses no skin. So in that respect, the black slaves got substantially more direct, in-kind compensation than we do. Various other goodies are provided to us, whether we want them or not (roads, schools, low-payout compulsory pension plans, subservient foreign nations, zillions of special interest funding...) but those five necessities are not.
But we do keep half of all the money we worked for, to spend somewhat freely.
"Free time" is another important factor. Antebellum slaves were given some. As far as I know, it was theirs to use as they saw fit. Sometimes teachers were provided, if any wished to learn. Often they found ways to make music, and a good deal of the distinctly American genre resulted - up to and including jazz. No restrictions or rules were applied, except of course the prohibition on travel.
Today the opposite applies. We have a good deal of leisure time, but almost all of it is subject to one or more intrusive government regulation. We can travel; but only with its permission; going and coming, we must be scrutinized by its agents. Even if by car, the vehicle must have certain features whether we want them or not, and speed is regulated and parking is only by permit. We can hike the hills, that have been in place since long before the dreadful day government first polluted the Earth; but a large fraction of them are under State or Federal control as "Parks", whose regulations we must follow. We can phone and email friends, but only with intense scrutiny by the NSA. Even in "free" time, we are subjects of the Nanny State.
Overall, and trying to disregard the vast technical and medical improvements that a relatively free capitalist society has produced since then, are we more enslaved or less, than Americans in 1860? That's for you do decide, but the foregoing shows it's not as easy a question as might be supposed. Clearly, we're much less free now (on average) at work, and probably in goodies directly provided; is that offset by improved liberty in our free time?
Both sets of conditions altogether pale, in any case, before the prospect of living free and independent with no government whatever. That's emancipation.