Why was New Jersey so Democratic (for Gov. and Pres.) from 1862 through 1892?

[Kevinstat]

This is a question I thought of asking a long time ago, back when there were a number of threads about "Why is [given state] so [Democratic or Republican]."  Reading the "Chat with The Mikado about cool history topics that interest you" renewed my interest in posing this question, but I figured I would give it it's own thread.  I just checked on Wikipedia and it turns out that in Congressional elections in New Jersey during this period, the two parties were relatively evenly matched, although things swung regularly.  The congressional element does give a good idea, however, as to when the change in voters habits (which might have manifested itself in a Gubernatorial or Presidential election had there been one after 1892 before 1895 (G) or 1896 (P) - New Jersey Governors served three-year terms back then) probably happened.  New Jersey voters elected an 8-0 Republican U.S. House delegation in 1894 after electing a 6-2 Democratic delegation two years before, and also sent Republican William Joyce Sewell back to the U.S. Senate after he had been unseated 8 years before (New Jersey's other U.S. Senator was a Democrat elected in 1892; Republicans won that seat when he declined to run for reelection in 1898).

Still, we're basically talking the Civil War and the "Gilded Age" for a period of Democratic predominance in New Jersey in races for executive office.  The state elected a Republican Governor in 1865 (coattails from the end of the war Lincoln/Andrew Johnson magnanimity to the south, perhaps) and went for Grant in 1876 (when his opponent was Horace Greeley, the "Liberal Republican" who had until recently before been one of the most vehement critics of the Democrats).  But besides that the Democrats won in or carried New Jersey in every Gubernatorial or Presidential election during that period.

Does anyone know or have any theories why?  Southern sympathies?  I know Deleware was still seen as a southern state back then (and it was a slave state at least going into the Civil War), but New Jersey was a Northern State and Republicans had been making gains there during the James Buchanan administration.  Immigrants?  Or a combination (more the former at first and then more the latter)?  That could help explain some of the fluctuation on the congressional side.  Unfortunately I have no knowledge of the composition of the Legislature during this period.

This basic question (perhaps in less detail) has probably been asked before on this forum, but still, any insight would be appreciated.

[FEMA Camp Administrator]

I'd assume it has to do with immigrants, though I think it should be noted that the Democratic nominees from the 1860's had all been Northeastern, and were typically New Yorkers. After 1892, however, it would make sense that the Republicans were gaining as the national environment was against the Democrats, and they became a much more agrarian party. I'd assume Democratic strength in New Jersey came and went with the era of the Bourbon Democrats.

[Kevinstat]

Thanks, Ready4Nixon.  I had forgotten to ask the obvious corollary which was what caused this period to end.  I figured it was part of the McKinley-era party system change, which seemed to start in 1894 nationally as well.  Your point about Democratic strength in NJ coming and going with the era of the Boubon Democrats goes along with that.