Fill in the "nth" in the following sentence.

Red Bank NJ is the nth largest municipality by population in the
United States.

I'm sure this info is available on census.gov in some form or another
but I can't figure out how to eek out the info.

Red Bank is technically a Borough.  The following page mentions it as
"Red Bank borough" http://eire.census.gov/popest/data/cities/tables/SUB-EST2002-09-34.pdf

Hello gadlen-ga,

The only way to calculate this appears to be state by state.  (There
is a custom table option at
http://factfinder.census.gov/servlet/DatasetMainPageServlet?_program=DEC&_lang=en&_ts=
 -- but it does not allow for a sufficient number of entries to create
a table of all incorporated places.)

The following table lists Red Bank as number 83 in New Jersey, with a
2002 estimated population of 11,839:

"Table 4. New Jersey Incorporated Places with Population over 10,000,
Ranked by July 1, 2002 Population: April 1, 2000 to July 1, 2002"
U.S. Census Bureau
http://eire.census.gov/popest/data/cities/tables/SUB-EST2002-04-34.pdf

So, 82 places in New Jersey have a greater population than 11,839. 
The figures for other states and the District of Columbia (the names
of which I will not list given time constraints, but which go from
Alabama to Wyoming, as shown at
http://eire.census.gov/popest/data/cities/subtab04.php) are:

48
3
32
27
337
36
20
3
1
135
51
1
13
185
64
27
29
28
27
10
19
45
77
76
34
55
7
15
8
10
14
71
58
9
145
34
40
55
8
30
8
42
175
37
3
34
61
11
62
6

This column adds up (on my calculator, anyway) to 2326.  Add to that
the 82 mentioned earlier for NJ, and you get 2408, which is the number
of incorporated places in the 50 states and DC with a higher estimated
population than Red Bank.  So Red Bank is number 2409.

- justaskscott-ga

That's exactly what I was looking for. You rock.