There was for about 15 years.

You can see a couple answers to a related previous question on this by /u/BlossumButtDixie and /u/needledknitter which runs through the basic overview here. In short, many states lowered the drinking age to 18 in concert with the 26th Amendment, road fatalities rose substantially in the 16-20 age bracket over the next decade, and a successful lobbying effort in the early 1980s prompted federal legislation to 'suggest' to states to raise it back by cutting off highway funds if they didn't. South Dakota and Wyoming were the final two holdouts that finally gave up in 1988; both did so extremely reluctantly, but given the significant amount of their budgets at risk they had no choice - which was the intention of the legislation.

For once, I'll make the rare decision to borrow a little from Wikipedia here to illustrate the changes since their maps make it vastly easier to see exactly how this worked (and since it's Friday and I really need a drink myself, also saves me the hassle of hand copying tables and Reddit formatting them.) Here's 1969, 1975, and 1983. Note the West Coast remaining at 21 throughout its entirety (and, in fact, for decades earlier); this had a bit to do with both leftover alliances between the Progressive and Prohibition movements - there were various initiatives over the years that tied the hands of the Legislatures, and one of my favorite pre-18th Amendment laws by the states was an 1873 one creating a 2 mile dry zone around UC Berkeley, which apparently worked well enough so it was expanded to other institutions of higher education in California - as well as concern over drinking off military bases by very junior enlisted that had to do with their experiences of World War II, like the Zoot Suit Riots.

While the lead up to Prohibition and then even more substantially its repeal created a whole state-by-state patchwork of changes to the drinking age as a whole and is more of a top level question, this is a useful gif that gives an overview of year by year changes since 1933. A few interesting things from it: Oklahoma didn't allow hard liquor sales until 1959 for anyone (discriminatory policies against Native Americans played a huge role in this - they were legally barred from drinking off reservation until after World War II), Kansas didn't repeal Prohibition until 1949 (the Anti-Saloon League had strong support in it long before National Prohibition - Charles Curtis made his early career enforcing state Prohibition laws as early as the 1880s) and Mississippi didn't repeal Prohibition until 1966, although that had far more to do with being able to selectively enforce Jim Crow nuisance laws against African Americans than a genuine effort to prevent Whites from drinking.

Also better suited to a top level question is the whole history of the 26th Amendment; I've written very briefly on it before, but its history really dates all the way back to the late 1800s when Republicans started initiating voter registration laws to suppress Democratic turnout in the North, Midwest, and West; as such, it had a very different origin and supporters than that which came out of Prohibition. What changed in the late 1960s was both the the moral argument about the disenfranchisement of servicemembers in Vietnam as well as a belief by both parties that the very loud political activities by young Boomers would translate into electoral gains for their particular party if 18 year olds were only allowed to vote. As it turned out, the latter belief has been dramatically disproved over the years as the 18-25 cohort has been at a historically significant turnout deficit to other age groups and has generally been very difficult to reach despite massive and costly outreach efforts. It is probably fair to view some of the lowering of drinking ages following its adoption as political calculus to try to appeal to that hard-to-reach demographic, but unfortunately off the top of my head I don't know any sources that have explicitly examined that particular connection between the two.