And what it can teach us about closing the gender gap.

It's easy to get nostalgic about the sort of mom and pop drug stores that have vanished from most downtowns. But loss of local color aside, maybe we shouldn't be so quick to mourn, because according to new research, the rise of big national pharmacy chains that have wiped them out has been a great triumph for women in the workplace. 

So write Harvard economists Claudia Goldin and Lawrence Katz, who find that being a pharmacist may now be the most female-friendly high-paying profession in America -- or, as they put it, "the most egalitarian." Male pharmacists still earn much more on average than their female counterparts. But that's almost entirely because they pull longer workweeks. Hour for hour, the men and women running the back counter of your neighborhood Walgreens make extremely similar wages -- a rarity in almost any line of work. 

The major reason, Goldin and Katz argue, is the giant chains that, along with pharmacy counters at big box stores and supermarkets, have replaced the local drug stores some of us remember so fondly. In the old days, being a pharmacist usually meant owning your own shop, or making significantly less money while working for someone who did. Men, who didn't have to worry about giving birth or taking time off to raise their child, made up the vast majority of the profession.  

Then came Walgreens (and CVS, and Rite Aid, and Walmart). As shown in the graph below, the fraction of pharmacists working at independent drug stores has been on a continuous decline since the the 1960s. Then, more than 70 percent were employed at mom and pop operations Today, just about 14 percent are. 

That giant, gradual change in the industry had two important effects. First, it became easier to work as a pharmacist part time. As Goldin and Katz note, pharmacists are fairly interchangeable (as far as highly skilled professionals go). For a large company like Walmart or Rite Aid, it doesn't make much difference if they hire one to work 40 hours a week or two for 20 hours each. And because there isn't much difference in value, the company can also pay all of them roughly the same by the hour. Second, it became less important to own your business (or a piece of it). In professions such as law, where making partner is the goal, working longer early on hours leads to a much bigger paycheck later in life. Not so for a pharmacist who isn't gunning to own their shop. 

These changes combined made the profession much more attractive to women, who were more likely than men to take a reduced workload so they could spend more hours at home with their young children. About 55 percent of pharmacists are women today, up from around 11 percent in 1974. The median woman working full-time as a pharmacist now makes 92 cents for every dollar a man earns, up from 66 cents in 1970. While not perfect parity, that still makes the gender gap "smaller for pharmacy than for almost any other high-wage profession," Goldin and Katz write. 

In some ways, this might seem like a frustrating story. The pharmacy industry underwent a unique transformation that made it more female friendly -- one which is hard to imagine in other, high paying fields such as law or accounting. But there might be some lessons here, in keeping with what Anne Marie Slaughter suggested in her Atlantic cover article, "Why Women Still Can't Have It All." The further away industries move from partnership and promotion models that penalize people who take a part-time track, the more it will encourage women to start and stay in high earning careers, and the sooner they'll be able to pull even men.