Demand and sales might be two different things - during and after Prohibition, it was much harder to procure alcohol than it had been before, so we shouldn't necessarily assume that sales = a reliable measure of demand.

As far as sales, though, Prohibition caused a dramatic drop in alcohol sales in the US, and Americans did not return to their peak pre-prohibition alcohol consumption levels (which were over 2.5 gallons per person per year) until the 1970s. That's counting beer and wine, but with all drinks converted to their pure ethanol content. Here's a (rather poorly made) graph.

Those stats only account for sales that there were receipts for and taxes paid on, so you can bet that alcohol consumption was much higher during prohibition than the graph suggests. Nevertheless, it's pretty clear that Prohibition actually did reduce the amount of alcohol that Americans drank on average, and that the effect lasted for some time.

To put all of this in perspective, it's worth noting that peak pre- and post-prohibition estimates of per capita alcohol consumption in the US don't even come close to the levels of the late eighteenth and early nineteenth century, where by some estimates per capita alcohol consumption was as high as seven gallons of ethanol annually.

so the key is that Prohibition isn't the prohibition movement. the movement was initially state and local before going national and while we call it a failure today it did dramatically change American drinking habits. in 1830 we drank 7 gallons of pure alcohol per year or 4 shots per day every day. That was the peak

so now the answer:

https://prohibition.osu.edu/sites/prohibition.osu.edu/files/Consumption1.gif

notice how by 1850 drinking had already been cut by over half from 1830! Post prohibition drinking habits didn't surpass pre prohibition habits until the 1970s. Though that might be misleading considering prohibition was repealed during the depression then WWII hit. So given the time prohibition was repealed it's not surprising it didn't pass pre prohibition levels but it still took 30 years of normalcy to get post prohibition liquor salves back to pre prohibition levels. Either way you look at it the major effect of prohibition had already been achieved before the national campaign though. How you interpret this data seems somewhat contested based on what i've read