There are hundreds of agencies in the United States. Just about all 50 states has at least one modeling agency, while the larger markets have dozens.
There are hundreds if not thousands of agencies out there, especially if you are asking how many there are worldwide.
Yes child modeling agencies are legal in the US. Many, although legal, are not legitimate. One way in knowing this is if they ask for all types of fees up front. If they do this, its a sign they may be trying to rip you off. http://ourcutebabies.com/articles/baby-modeling/modeling-upfront-fees.html
Many modeling agencies will not accept a 13 year old. But, there are many big agencies in New York, Flordia, and California.
There are no modeling agencies in the OC. You will need to seek out agencies in Los Angeles and San Diego.
It sounds like you'll want to look into glamour modeling. There aren't many modeling agencies that have glamour modeling divisions but there are online glamour modeling agencies you may want to look into. You can do an online search for glamour modeling agencies in Portland and see what comes up.
US Talent Management 235 Alexander St Second Floor Rochester, NY 14607 Your best bet is to go with modeling agencies in New York, New York.
Unfortunately, the Michigan area is not a viable modeling market, which means that there are not many credible, legit and reputable modeling agencies for teens. There are one or two agencies that appear legit but they do not specialize in teen models.
Petite modeling agencies are few and far in between because there is no demand for them but you can try a shot at commercial/print modeling agencies: - Angie's Model & Talent Agency
Yes. There are many modeling agencies in London, however there are height requirements that must be met--even for teens. This link contains all the modeling agencies in the London area. Be sure to check their websites and note the requirements needed in order to submit your teen: http://www.kmodels.com/London-modeling-agencies-links1.htm
Skip modeling schools and deal directly with the modeling agencies. Here is a link to modeling agencies in Arizona, whose websites you can check out to see what their requirements are and what photos you need to send in: http://www.joeedelman.com/agencies/agency_az.php
If you are looking for modeling agencies in Newry, Pennsylvania, this link contains all the modeling agencies located in the Pennsylvania area: http://www.joeedelman.com/agencies/agency_pa.php
This link will show you three modeling agencies in the Mauritius area...there aren't many: http://www.jurgita.com/agencies/mauritian-agencies