Tuesday is Equal Pay Day, which was invented by an activist group two decades ago to draw attention to the wage divide between men and women.

The day comes in April, roughly marking how many extra months women would have to work into the new year to make what men made the year the year before.

The divide in pay has narrowed since 1996, but women in the U.S. still make about 79 cents for every dollar a man earns, according to Census data.

Here are some basic facts about that persistent gap:

In California, the difference is $8,000 per year

A woman who works full time in California makes a median of $42,486, compared with a median salary of $50,539 for a man, according to an analysis of Census Bureau data conducted by the National Partnership for Women and Families, an advocacy group.

That makes for a difference of about $8,000 per year, or the average cost of six months of rent in the state.

Latina women are further behind — they earn just 43 cents for every dollar earned by a white man in California. Black women earn 63 cents, and Asian women earn 72 cents.

In total, women in the state would earn $38.8 billion more per year if their pay were in line with men.

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Women are in lower-paying jobs

Most of the pay gap amounts to an occupation gap: Women tend to go into fields where salaries are lower and perform jobs that pay less.

That’s a key takeaway from a January study by two Cornell economists, Francine Blau and Lawrence Kahn, published by the National Bureau of Economic Research. They found that 51% of the difference in the compensation of women and men is related to the fact that female workers are more concentrated in underpaid sectors, like nursing or education, and in lower-level roles.

Women have managed to overtake men in education and almost completely catch up in experience over the past three decades. But the divide in the types of careers women and men gravitate toward still persists, and seems to hold back women's pay.

Women ask for less money

When hunting for a new job, women ask for lower salaries than men, and they leave the table with less money, according to a study published Tuesday by Hired, a website that connects employers to job-seekers.

The website studied data from 100,000 salary offers for tech, marketing and sales jobs, and found that nationally women ask for an average $14,000 less in compensation than men overall. Employers offered women about 3% less than what they offer to men to fill the same position, with the same job title, the analysis showed.

In Los Angeles, women ask for $10,000 less than men, and take home $8,000 less. In San Francisco, what women say they want comes to almost $12,000 less than what men ask for, and they receive about $9,000 less.

Those expectations mattered; women who asked for bigger salaries than men ended up getting them.

Women just entering the job market, with under two years of experience, expected to get paid a little bit more than men, the Hired study found. More experienced women expected to get paid less. The junior women left negotiations with salaries that were 7% higher than those of junior men.

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Discrimination is probably still happening

The Cornell study found that a chunk of the pay differential could not be explained by measurable qualities of American workplaces. The authors say that one hard-to-quantify factor at play could be discrimination.

Indeed, research has shown that many women with the same credentials who work in the same exact jobs as men earn less. A 2015 Bloomberg analysis of more than 12,000 MBAs found that eight years out of business school, women earn 20% less than the men they graduated with.

The divide persisted within industries, job functions and for people who got their degree from the same business school.

Census data also show that women are paid less than men within the industries that most Americans work, including healthcare, education and manufacturing, and within specific jobs, like sales, management, production and administrative functions.

What’s more, it seems that women cannot always choose to make more than men by shifting into a higher paying field. A comprehensive study of census data from 1950 through 2000 found that as women began working in occupations that once were dominated by men — as biologists or designers, for example — the compensation in those jobs declined.

For news about the California economy, follow @NatalieKitro on Twitter.

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