On the strength of a few albums in the mid-90s and early 00s, Shania Twain became the top-selling female country artist of all time, a title she holds to this day.
Her 1997 album Come On Over received a rare double-Diamond designation and remained on the Billboard 200 for more than a year while topping the country chart for 50 weeks. It was a crossover blockbuster, with pop country songs everybody knew by heart and memorable music videos showcasing Twain’s pin-up appeal.
And yet… that album somehow did not produce a #1 hit. Neither did Twain’s other multi-Platinum efforts, The Woman in Me (1995) and Up! (2002).
The closest she came was with today’s SOTD, the third single from Come On Over, which peaked at #2 on the Hot 100. ‘You’re Still the One’ actually reached that spot twice, first for a single week and later for two straight months. The first time it was blocked by ‘Too Close’ by R&B group Next (who?), and during the longer stretch it was kept from #1 by Brandy and Monica’s duet ‘The Boy is Mine.’
Come On Over produced two more top-ten hits in ‘From This Moment On’ (#4) and ‘That Don’t Impress Me Much’ (#8). ‘Man! I Feel Like a Woman!,’ which I know better than any of the others, peaked at #23. Twain’s subsequent releases found some crossover success but resulted in only one top 20 hit (2003’s ‘Forever and For Always’).
Twain’s failure to reach #1 is emblematic of the struggle women in country have had finding breakthrough success. While 21 country songs by male singers have reached the top spot, only five by women have achieved the feat. Two are by Dolly Parton (‘9 to 5’ and ‘Islands in the Stream,’ which was also a #1 for Kenny Rogers). Two are by Taylor Swift (‘We Are Never Ever Getting Back Together’ and ‘All Too Well (10 Minute Version)’). And the latest is Beyoncé’s ‘Texas Hold ‘Em.’
When I first saw you, I saw love
And the first time you touched me, I felt love
And after all this time
You’re still the one I love
Mmm, yeah
[Verse 1]
Looks like we made it
Look how far we’ve come, my baby
We mighta took the long way
We knew we’d get there someday
[Pre-Chorus]
They said, “I bet they’ll never make it”
But just look at us holdin’ on
We’re still together, still goin’ strong
[Chorus]
(You’re still the one) You’re still the one I run to
The one that I belong to
You’re still the one I want for life
(You’re still the one) You’re still the one that I love
The only one I dream of
You’re still the one I kiss goodnight
[Verse 2]
Ain’t nothin’ better
We beat the odds together
I’m glad we didn’t listen
Look at what we would be missin’
[Pre-Chorus]
They said, “I bet they’ll never make it”
But just look at us holdin’ on
We’re still together, still goin’ strong
[Chorus]
(You’re still the one) You’re still the one I run to
The one that I belong to
You’re still the one I want for life
(You’re still the one) You’re still the one that I love
The only one I dream of
You’re still the one I kiss goodnight
You’re still the one
[Interlude]
(Ooh, ooh, ooh)
Yeah
[Chorus]
(You’re still the one) You’re still the one I run to
The one that I belong to
You’re still the one I want for life, oh, yeah
(You’re still the one) You’re still the one that I love
The only one I dream of
You’re still the one I kiss goodnight
[Outro]
I’m so glad we made it
Look how far we’ve come, my baby
Meet Me In Montauk 
I’m not sure I agree with your conclusion that “Twain’s failure to reach #1 is emblematic of the struggle women in country have had finding breakthrough success.” While there is an imbalance as to number one hits on the Billboard pop chart, at least two or three of the five country women number ones are not really country songs, and I suspect that may be true for several, if not the majority, of the 21 country men number ones. I’m also not sure it’s been harder for women country artists to have breakthrough success than it has been for women artists in general to have commercial success as compared to the men, both in country music and pop music.
That’s just it, though.. all of the male #1s are straight up country. Not so for the women. Meanwhile, Mariah Carey, Rihanna, and Taylor Swift have more #1s than any male artist not named Drake or Elvis. It’s definitely harder for women to find commercial success in country.