Yeah I think Blaine would have won too with a New Yorker, but that case basically a breeze or nominal change could change everything. Just not sure if it mattered generally cause VP's were so unimportant. People wouldn't be giving said picks the attention they do today so just unsure in that regard.Generally New Yorkers liked voting for their own people:
1876: Both presidential tickets had a New Yorker.
1880: The GOP prez ticket had a New Yorker and won.
1884: The Dem prez ticket had a New Yorker and won.
1888: Both presidential tickets had a New Yorker.
1892: Both presidential tickets had a New Yorker. (I checked and Harrison's 1892 VP choice Whitelaw Reid also appears to have been from New York; what threw me off is that he was born in and spent his early life in Ohio.
1896: No presidential ticket had a New Yorker--though the winning 1896 GOP ticket came close by having a New Jerseyite in the VP slot.
1900: The GOP prez ticket had a New Yorker and won.
1904: Both presidential tickets had a New Yorker.
1908: The GOP prez ticket had a New Yorker and won.
IMHO, given Blaine's extremely narrow margin of defeat in NY in 1884, even with that 3-R's gaffe, Blaine would have probably still won NY had he actually had a New Yorker on his ticket.
As for 1892, please keep in mind that the Dems won the NY's governor and lieutenant governor jobs just a year earlier--specifically in 1891. So, it wouldn't have been impossible for Cleveland to win NY in 1892 even without the Populists. Please keep in mind that 1890 resulted in a huge Democratic landslide in the US Congress.
As for Chet Arthur, I think that he was picked both to appease the Stalwarts and to carry NY. Likewise, I suspect that Levi Morton was picked in 1888 to likewise carry New York for the GOP ticket that year. Ditto for Whiteland Reid in 1892--though that GOP ticket failed to actually win.
Barely--1896 and 1948 were both close and were 52 years apart.
Midterm elections that contradicted the Presidential elections both before and after are a super common trope of US political history in all eras. Politics was bigger in the US in the 19th century prior to major sports and haven't really looked but I imagine a substantially smaller electorate voted in the Midterms than for the Presidency. Midterms have different electorates and parties were not ideology based as there were people from the far left to right in both political parties. Saying the 1890 nominee for governor was a Democrat isn't enough context as the kind they would be makes a huge difference, anyone of any political ideology could be a Dem or a Repub and these differences were fought over at the primary level while today we've outsourced that to the general election. New York interestingly which is a one party system largely operates the same way with all viable candidates with very different political ideology's all being Democrats. Political parties in the US were more like ethnicity's if your parents were Democrats or you had some affiliation with the local machine, you were a Democrat and it had little to do with your actual opinions you'd just be pushing for people within that party who shared them.
I don't consider 1896 close. It was the closest of the three Bryan elections and it might be a tad extreme to call it a landslide but it would have required the swinging of a multitude of not very close states. Cali was a rare close state but it had 8 electoral votes back then. But it's weird in the 1800s basically every election from 1844 to 1892 was close barring the ones the Southern states sat out(1860 when the Dem party split wasn't close for similar reason) as in one or two very close states change the outcome(it was almost always New York that was the state in question though in 1856 it was 3 other close states, which ones I don't recall). After 1892 there were 4 close elections up until the 1991 rule(1948,1960 and 1976) 100 years later(and then even more time after that without one). So that's a very interesting shift and shows that in the interim between that New York era and the present, the concept of "swing states" deciding an election and picking a VP to appeal to said crucial state wouldn't be explainable like it would be in the 19th century and today cause it almost never came down to that.
And the Ohio trend is weird you got me looking into it, it's just insane. Whether it be birth, growing up or just generally being from Ohio, there just was a bizzare tendancy for Presidential and Vice Presidential nominees to be from Ohio. Today it's a swing state, arguably THE swing state and it would make sense but back then it's just bizzare and there's no ryhm or rhythm to it, you a lot of cases like Reid where someone just happened to be Ohioan. Harding and Garfield were compromise candidates(and Garfield was replacing an Ohioan who he was supporting as the would be nominee) and Grant just happened to come from there as well. It was mainly a Repub thing. Check out this crazy trend, 1868 and 1872 Grant born in Ohio. Succeeded by the Governor of Ohio in 1876 who is in turn succeeded by a Congressman from Ohio who'd been supporting the candidacy of a Senator(Sherman) from Ohio. In 1888 Harrison is the Republican nominee and while he's a Senator from Indiana he was born in Ohio which his grandfather had represented in the Senate. He's the nominee twice in 1892 even having a running mate from Ohio and then in 1896 the Republican nominee is...you guessed it ANOTHER congressman from Ohio! McKinley is assassinated and replaced by TR, who in 1908 chooses as his successor a man from OHIO! Then in 1920, the nominees both compromise candidates are the Senator and Governor from Ohio respectively. And yet in 1924 the Republicans picked a Vice Presidential candidate from Ohio yet AGAIN! Like this whole story I just told took place over almost 60 years.
Another interesting thing I discovered is while NY obviously was the closest thing to matching Ohio at producing Presidential and Vice Presidential nominees, neighboring Indiana seems like a strong third, especially in regards to Vice Presidential candidates(though Harrison represented Indiana in the Senate and Wilke was from there and they were Presidential candidates). Seeing that Indiana borders Ohio shows an extreme tenancy for the parties to nominate someone from that specific part of the MidWest.