These Are the U.S. States Where the Gender Pay Gap Is Widest In some states, the average man makes $15,000 more than the average woman.

Today is this year's Equal Pay Day, which represents the amount of extra time the average woman would have to work full time -- 100 days -- to make the same amount of money the average man made in the previous calendar year.

While this day is meant to raise awareness about the discrepancy between men and women's pay in the aggregate, some women would have to work even longer into 2018 to reach the same annual compensation as their male counterparts. This is true for women of color, on average, and it's also true for women who live in certain U.S. states.

Expert Market, a U.K.-based product comparison site, calculated the pay gap between genders in all 50 U.S. states and Washington, D.C., using wage data from the National Women's Law Centre.

The state with the widest gender pay gap is Louisiana, where the average man earns $15,238 more than the average woman per year. Louisiana's pay gap is more than the combined pay gaps in California (ranks 49th at $5,928) and New York (ranks 50th at $5,766). The state with the narrowest pay gap is Florida, at $5,474.

Related: Women Won't Achieve Equal Representation in Business Unless Men Help Change the Status Quo

In other words, women in Louisiana earn 70 cents for every dollar men in Louisiana make, or they spend 10.5 hours of each 35-hour work week "working for free," as Expert Market's research team puts it.

While the researchers didn't dig to find out why some states have wider pay gaps than others, they noted that in recent years, California and New York have banned employers from asking job applicants about their previous salaries. Doing so is thought to mitigate pay inequality: If a woman was underpaid at her last job, her pay at her next job should not be based off the previous figure.

"In order to fully understand why the gap is so significant in places like Louisiana and Utah, we'd need much more data about things like the representation of men and women in senior positions and specific pay brackets," Expert Market researcher Jessica Laporte told Entrepreneur in an email.

Expert Market also noted that earlier this month, the U.K. government ordered thousands of companies to disclose information such as employee salaries and titles to suss out cases in which women are being underpaid within organizations.

Pay inequality is ultimately a systemic issue, and policy change is one way to address it. The World Economic Forum in fall 2016 forecasted that the gender pay gap won't be closed worldwide until the year 2186. Factors such as literacy and education rates, health and survival rates, women's participation in government and more are correlated with pay gaps in different countries.

However, entrepreneurs and employees themselves have the power to make small changes to overcome pay discrepancies at the organizational or individual level.

Women can practice various negotiation tactics when asking for initial salaries and raises. Companies can be transparent about what certain positions pay so that candidates who underestimate their worth don't settle for being underpaid. Organizations can offer flexible schedules to employees who are parents so they don't have to choose between childcare and advancing in their careers. Women can also help other women by coaching them and making sure their contributions are heard and valued at work (women can ask other women to help them do this).

These are just a few of the steps anyone can take at the micro level to start to close the gender pay gap. In the meantime, here are the U.S. states ranked in order from largest gender pay gap to smallest, according to Expert Market.

1. Louisiana $15,238
2. Utah $15,077
3. Washington $13,808
4. South Dakota $13,382
5. Connecticut $13,229
6. West Virginia $12,801
7. Indiana $12,717
8. Montana $12,517
9. Oklahoma $12,055
10. Alabama $12,022
11. Wyoming $11,896
12. New Jersey $11,737
13. Iowa $11,594
14. Ohio $11,477
15. Massachusetts $11,202
16. Michigan $11,044
17. Virginia $11,019
18. Illinois $11,003
19. Wisconsin $10,959
20. Idaho $10,902
21. Kansas $10,800
22. Pennsylvanica $10,733
23. Nebraska $10,653
24. Oregon $10,483
25. Washington, D.C. $10,435
26. Mississippi $10,389
27. Maryland $10,074
28. Missouri $10,029
29. South Carolina $9,995
30. North Dakota $9,948
31. Rhode Island $9,859
32. Texas $9,775
33. Kentucky $9,262
34. Delaware $9,153
35. Minnesota $9,068
36. New Hampshire $9,031
37. Arkansas $8,914
38. Alaska $8,904
39. Nevada $8,645
40. Georgia $8,434
41. Arizona $8,420
42. North Carolina $8,193
43. Hawaii $8,149
44. Colorado $8,058
45. Tennessee $7,745
46. Maine $7,650
47. New Mexico $7,629
48. Vermont $6,718
49. California $5,928
50. New York $5,766
51. Florida $5,474

Related video: Don't Have Money to Pay Employees? You Can Still Build Up a Great Team.