Revelator

The entire song take the form of the singer revealing to us how she feels about herself and her mental and emotional state.

The first verse: The singer reveals and warns us that she is untrustworthy but whether this statement is true will only be revealed in time. Hence "time's the revelator".

The second verse: The singer reveals that she is on her own and a fortune teller predicts her future. But the predictions turn out false thus every word dates the fortune teller as time reveals and disproves her predictions.

The third verse: In this verse the singer is tired of her current situation. Days getting straighter hints at a lose of adventure, discovery, and a fulfillment.

The forth verse: The singer escapes, or dreams of escaping, Corning and returns to California where life will be better. She then calls herself the Queen of Fakes and Imitators, which she told us in the first verse. Time will reveal all.

Definitions: The "Katy" refers to the Missouri–Kansas–Texas Railroad. "She Caught the Katy (And Left Me a Mule To Ride)" is a blues song.

Revelator is one who revels.

Corning is a town in New York.

Cali is short for California.

I learned to play/sing this song and in so doing listened to it literally hundreds of times. Personally, I don't think any of the online lyrics get it exactly right. My version is below although if anyone has evidence I got something wrong or additional insight into the meaning of the lyrics, I'd love to hear it.

I'm pretty sure the song is about Gillian Welch's experience in the country music business. Although most country musicians were from Tennessee or somewhere in the south and grew up playing country music, Gillian grew up in California and didn't really start playing country music until she was finishing college at UC Santa Cruz. Verse 1 conveys the idea that she was seen by some industry insiders as a "pretender" who was not what she was "supposed to be", and a "traitor". As her Wikipedia page points out, her debut album Revival was criticized on these grounds.

The second verse suggests that being an outsider was a significant obstacle to her professional career. While insiders "caught the Katy" (a famous railroad line) and rose quickly to success, she was left with "a mule to ride" and her success took longer. Ultimately however "the fortune lady came along" and "walked beside", and Gillian managed to succeed in the business. The third verse ("every day is getting straighter") also conveys the idea that things got better over time.

After finishing her education, Gillian moved to Nashville to pursue a country music career but verse 4 suggests that living in Tennessee was frustrating and made her want to move back to California ("Leaving the valley...out of sight...go back to Cali"). By the way, I think "move the fader" is a reference to a mixing board in a recording studio and may refer to how moving from Nashville back to California would turn down the volume of her critics.

Over time, of course, Gillian overcame all these obstacles, became a star, and was vindicated. Time revealed that she was not the "queen of fakes" or "an imitator" (outro), but that her music is authentic and powerful. Time's the revelator.

Here's my version of the lyrics:

Darling, remember when you come to me
I’m the pretender and not what I’m supposed to be
But who could know if I’m a traitor?
Time’s the revelator

They caught the Katy and left me a mule to ride
The fortune lady came along, she walked beside
But every word seemed to date her
Time’s the revelator, the revelator

Up in the morning, up and on the line
Drivin’ to Corning and all the spindles wind
And every day is gettin’ straighter
Time’s the revelator, the revelator

Leavin’ the valley, f***in’ out of sight
I’ll go back to Cali where I can sleep out every night
And watch the waves and move the fader
Time’s the revelator, the revelator

Queen of fakes, an imitator
Time’s the revelator

It's about an unfaithful lover who questions their own commitment.

Time is revelator, it reveals the true intentions driven by doubts in a relationship that is driven by the trials and tribulations of daily life.

It's so obvious there is pain of regret and pain caused by unfaithfulness to partner.

Move fader is moving away from guilt.