Parts of lower Manhattan, NYC have been strongly Democratic since the time of Martin Van Buren's Presidency.
you are surprisingly right. I always thought that New York (Manhattan, Brooklyn, Bronx) were all strongly republican until the Great Depression. Take a look at this link: http://en.wikipedia.org/wiki/70th_Congress. I'm not sure how the numbering system worked back then but i thought low numbers = new york city and high numbers = buffalo. Notice how numbers 2 through 18 were democratic. I'm assuming most of those districts had high jewish and ethnic catholic populations.
However, in the state of New York, if one was to get outside of the city of New York, it was strongly republican. Even FDR lost almost all the counties in his home state all four times. The only reason he won his home state is because of the city of New York.
As far back as the late 1800's, GOP strength was concentrated in the Upstate areas and in some enclaves throughout the city of New York like the East side. The presence of Irish, then italians, and then other minorities have given the Democrats a decided edge in most elections in New York City going back to the 1840's.
There was a lot of penetration in 1920 into New York City because of the Irish abandoning the Dems over Versaille. However in 1922 these were wiped out for the most part and the Democrats actually controlled the delegation from 1923-1947. Even Coolidge winning NYC couldn't regain a majority of NY seats.
http://en.wikipedia.org/wiki/United_States_congressional_delegations_from_New_YorkSome people like Fiorella La Guardia and Jacob Javits represented Manhattan seats that really weren't Republican seats and were won largely because of a personal vote for those individuals. The East side district had a GOP machine of sorts and elected people like Coudert and then Lindsay and Green before it collapsed in the 1990's.
The GOP dominance over Long Island and other areas, that are often whined about having been lost, existed for only a decade in the 1950's and early 1960's. After that they were constantly competative with seats going back and forth in different elections with an exception being the 4th seat (sometimes numbered something else).
