What is the average number of sexual partners americans have had over
their lifetime (both male and female). Specifically I'd like to know
the average number of partners americans have had by/at age 30, but
the average for different age groups would also be much appreciated.
Links to more than one study/poll would be appreciated. Thanks!

Perhaps this will be of interest:

http://www.aegis.com/news/pr/2001/PR010231.html

http://www.durex.com/nl/gssContent.asp?intQid=23&intGSSYear=01&intMenuOpen=8

It is difficult to answer your question concisely for a number of
reasons. Primarily any survey that is carried out is likely to be
flawed; more conservative people may wish to lie about the amount of
sexual partners they have had (even in an anomynous survey) and less
inhibited individuals often increase their number individually
Psychology professor Dr. Norman Brown suggests that men often
overestimate the amount of partners they?ve had
(http://www.aphroditewomenshealth.com/news/20030216222118_health_news.shtml)
and therefore a hint of scepticism should be held when reading
statistics!

It is A FACT to state that over recent years sexual behaviour
(especially in the younger generations) is increasing dramatically
According to Marica Mogelonsky (American demography study) in 1994 the
average American man had six sexual partners over his lifetime, it is
now estimated that most males reach this number by age 25 and females
by age 30 (American demography study 2004); the following links show
interesting information relating to the continuing promiscuity of
younger Americans http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Teenagers_sexual_behaviour?Open
& http://www.agi-usa.org/pubs/journals/3027198.html &
http://clearinghouse.mwsc.edu/manuscripts/455.asp.

As stated above it is difficult to state an exact average of sexual
partners and anybody who attempts to do so is being extremely naïve.
Based on the various articles I have researched with particular regard
to the demographic studies I would estimate the number to be around
7-8 for males by the age of 30 and 5-6 for woman; although in the
modern society we live in the younger generations are often reaching
these numbers of sexual partners significantly quicker! Changing times
means statistics may rise or fall depending on changing social
attitudes however currently I would suggest observing any studies etc.
you may read with an air of scepticism.

Hope this helps there are some more interesting links below:

http://community.healthgate.com/GetContent.asp?siteid=acare&docid=/healthy/sexuality/1998/sexusa/index

http://dataguru.org/love/sexstd/npart.asp 

://www.google.com/search?q=average+sexual+partners+2004+america&hl=en&lr=&ie=UTF-8&start=10&sa=N

http://www.guttmacher.org/pubs/journals/2704801.html