In 2001, it was confirmed that there was no manufacturer of black powder in operation in the US. The last US manufacturer (which I believe was DuPont?) lost their factory in an accident and as of 2001 had chosen not to resume production. There was/is some demand for it, so in the decade since a few small suppliers have come into existence, but I don't have information at hand on whether they actually make the powder or just remix and package imported powder under new brand names.

Black powder is simple enough to make that early farmers often made their own for purposes like stump blasting, and commercial black powder was still in use when the railroad blasted its way through to Hutchinson, Kansas in the mid/late 1800s (souvenir pictures at hand), but more modern explosives are much safer and it's seldom used much anymore.

Black powder (original or as Pyrodex) is still used for "blanks" and possibly for the "flash-bang" type of assault/crowd control charges popularized by a couple of TV "spy epics." (I've never seen a documented use of "flash bangs" by police, but ... ) The uses in blank cartridges are due to the pressure regressive burning (a chemical characteristic) that prevents pressure buildup if the gun isn't too clean, impressive smoke, and sometimes for the bright burning powder ejected due to slow/incomplete burning in the gun.

A disadvantage of black powder is that the residues left in the barrel are extremely corrosive, partly because they're mostly hygroscopic and absorb moisture, and "extensive cleaning rituals" are necessary after each use that are generally unneeded with more modern propellants. In fixed cartridges, corrosive primers continued in some use long after smokeless powder went away, but more modern cartridges generally use noncorrosive primers and minimize the need for very frequent cleaning almost entirely, with congealed lubricants being more of a problem than powder/primer residues.

Chemically, most "smokeless" powders are slightly pressure progressive, but this characteristic can be controlled by details, mostly the geometry of the individual "grains" that make the burning "rate regressive" or "rate progressive.

A "disk" shaped grain will burn on the surface so that the burning surface is relatively constant until it's all gone. This powder grain shape is used in many small arms loads.

A solid rod that burns mostly on the cylindrical surface reduces the burning surface as it burns, so the rate at which gas is produced slows down as the grains are consumed. Sometimes used in shotgun sized cartridges to reduce "muzzle report."

A cylindrical tube can be nearly "rate neutral" since the increase in burning area in the hole offsets the decrease in burning area on the outside.

Multiple lengthwise holes in a cylinder can produce much more increase in the holes than the decrease on the outer cyclinder surface, and can make a "rate progressive" grain.

Highly progressive powders are generally used only in very large bore guns, where the bore volume to be filled with gases increases at increasing rate as the projectile accelerates inside the gun, and a lot of gas is needed to maintian the pressure in the expanding tube volume.

So far as is reported, even the largest naval guns have used "smokeless" powder since it's been available, although it remains "separate loaded," with the projectile rammed into the tube followed by separate bags (or cans) of "powder." I don't have documentation on when the transition was made, but it's been quite a while.

Traditional black powder would possibly (likely?) still be used in large guns for ceremonial "salutes" since the extra smoke is impressive.

ALL PROPELLANTS are "deflagrating" compounds when used as intended. That is, they burn and DO NOT EXPLODE.

Explosives, that DETONATE, are an entirely different matter, and for the most part have nothing much to do with guns.

(Or so it was taught to the US Army Ordnance gang half a century ago.)

John