Saddle River has smaller taxes as there is less demand on the town, public needs increase taxes. The population is 3 x larger in USR, so more demand. Sports & parks offered by the towns is significantly lower in SR as an example for demand.
Both towns offer Northern Highlands High School which is in Allendale, Saddle River offers Ramsey HS as well, although most children residing in SR after elementary school opt for private school.
In my opinion as a resident of Saddle River the towns will never be combined.
Same zip code because there is only one post office for both towns and its located in SR, keep in mind SR does have a public library either, you pay a fee as an out of towner to use the facilities that the library offers.
Saddle iver has homes from under one million to 15 million, USR $400,000 to $3,500,000.
I hope this answers some of your questions, if you have any desire to move into these towns and you have children, my first choice would probably be USR for you and your family.
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