Abraham, Martin & John is a good one: because it seems the good they die young.
Lightning crashes by Live: because it hits home.
Fields of gold by Sting: I don’t know why
The End by the Doors: mainly because it’s a break-up song at its core, “it hurts to set you free but you’ll never follow me”
The boxer by Simon & Garfunkel
Two come to mind (surprised they haven’t been mentioned yet):
My Immortal by Evanescence
and
Joey by Concrete Blonde
That second one really so. The lyrics are so simple and yet she sings them with so much emotion (not to mention her breathy, rasping voice). 
I wallow in Marianne Faithfull’s “The Ballad of Lucy Jordan” because it is so brilliantly desperate and sad and real. But it kind of has a happy ending; the woman loses her mind and escapes her misery.
There are several songs that either make me cry OR I can’t listen to them all the way through or I’ll bawl my head out, but the reasons behind them are unclear even to me.
“Uninvited” by Alanis Morrisette.
“Don’t Let It Bring You Down,” written by Neil Young, as performed by Annie Lennox - “American Beauty” soundtrack
“The Lighthouse” by Nickel Creek - on the first few notes from the guitar my eyes well up and I have to leave the room, which really sucks, because I love that song.
Those three INSTANTLY spring to mind, but there are a truly unnerving number of pieces of music that crank the waterworks on full blast.
Another vote for the Gorecki, when the womans voice comes in it’s just the most beautiful thing.
Amazing Grace always gets me, doesn’t make me cry but never fails to move.
A song that always starts the tears flowing and that I find very hard to listen to is Harry Chapin’s “Cat’s In the Cradel”
And for the punch below the belt I nominate Mother by John Lennon.
When my son was about 3 years old, he could be brought to tears by someone singing the Hee-Haw song, “Where, Oh Where, Are You Tonight?”
We only did it a couple of times, honest.
I can add “Sometimes Love Just Ain’t Enough” because it really hit home for me while I was dating a guy that I knew loved me, but I just didn’t feel the same and I knew I was going to break his heart. especially the line -
“I don’t want to use you, just to have somebody by my side.”
Also, “The Dance” - because said guy decided it was the perfect song for our doomed relationship
“Christmas in Dixie” by Alabama
I’m such a sap.
I was gonna say that! I got to know this song from Gordon Bok’s version.
I’ll add one more: “Kilkelly”, by Peter Jones, fashioned from emigrant letters written to a family in America from a family in Ireland from 1850 to 1900.
(The version I have is by Mick Moloney).
Fred Jones, Pt. 2 by Ben Folds – a kind of Death of a Salesman in a 3-minute pop song
Fred sits alone at his desk in the dark
There’s an awkward young shadow that waits in the hall
He’s cleared all his things and he’s put them in boxes
Things that remind him: ‘Life has been good’
Twenty-five years
He’s worked at the paper
A man’s here to take him downstairs
And I’m sorry, Mr. Jones
It’s time
Martha by Tom Waits
It Can’t Rain All The Time by Jane Siberry (from The Crow soundtrack)
I’m a total sap, so I have to admit to finding it hard to choke back the tears when I hear The Fields of Athenry, The Wreck of the Edmund Fitzgerald and U2’s Mothers of the Disappeared.
Ok, so I’m going to admit this in public. I’m not sure why, perhaps I just want to hear the mocking sounds of your laughter.
I started bawling like a baby last night - I was listening to “Roll On” from Alabama. Then “Carolina Mountain Dew” came on - and it was the end for Missy.
Those songs get me, too! (sniffle)
30kft, be Assemblage 23. I never play it, because I burst into tears.
Eleanor Rigby
Vimy, by Tanglefoot
I usually have to skip “And the Band Played Waltzing Matilda”, and “Kilkelly, Ireland”, which nobody has mentioned - it’s in the form of a bunch of letters to a son who’s gone to America, giving all the updates - obviously he never comes home, and his mother dies. It’s just so, so sad. Oh, and “Cats in the Cradle”.
But I actually threw a cd away once because I kept forgetting to skip Emmylou Harris singing “Bang the Drum Slowly”, and it makes me think about how my dad’s getting older and will die one day.
Yes 
more info
But here in this graveyard that’s still no-man’s land
The countless white crosses stand mute in the sand
To man’s blind indifference to his fellow man
The whole generation was butchered and damned
Did they beat the drums slowly?
Did they play the pipes lowly?
Did they bugles carry you over as they lowered you down?
And did the band play ‘The Last Post’ in chorus?
Did the pipes play ‘The Flowers Of The Forest’?
Include too Emmylou Harris’s “Bang the Drum Slowly”:
Gone now is the day and gone the sun
There is peace tonight all over Arlington
But the songs of my life will still be sung
By the light of the moon you hung
I meant to ask you how to plow that field
I meant to bring you water from the well
And be the one beside you when you fell
Could you tell
Bang the drum slowly play the pipe lowly
To dust be returning from dust we begin
Bang the drum slowly I’ll speak of things holy
Above and below me world without end
You mentioned JKellyMap’s and I mentioned yours! Great minds (and in my case, slow fingers) 