San Lorenzo is a country in Central America where Arnold's parents Miles and Stella lived, worked, and explored for many years. It was also the place where they disappeared for over 10 years before they were finally rescued. During Miles and Stella’s time in San Lorenzo, Arnold was born in an abandoned temple that was near the foot of an active volcano.
Numerous glimpses of San Lorenzo are given in the episode "The Journal", in which Arnold finds his father's journal and reads about his adventures in the country. At the end of the episode, Arnold finds a map of the region in San Lorenzo where his parents went before they disappeared. The main events of Hey Arnold!: The Jungle Movie take place in in this country.
The areas of San Lorenzo that have been seen are covered by jungles. There is at least one active volcano, at least one navigable river (roamed by the river pirate Lasombra), several waterfalls, and the remains of numerous architectural structures built by the Mayans, among other civilizations. A large body of water was also seen, but it is not clear if it was a sea or a large lake. Considering these factors, San Lorenzo is most likely located somewhere between Honduras, Guatemala, and Belize.
San Lorenzo is also home to a mysterious group of people known as the Green Eyes, who are said to be the country’s original inhabitants. Other ethnic groups include Mestizos (including Eduardo) and Amerindians who speak an unknown language. Besides having human inhabitants, San Lorenzo also hosts a wide variety of jungle animals, including butterflies, snakes, Jaguars, monkeys, and wild boars, to name justa few species. In addition, Abner was most likely born in San Lorenzo, as he was a wedding present to Miles and Stella from the Green Eyes. This could mean that San Lorenzo produces (or at least imports) a few breeds of livestock.
- San Lorenzo is also the name of an insular nation described in Kurt Vonnegut's book Cat's Cradle.
- Craig Bartlett confirmed in his second interview on The Arun Mehta Show that his use of the name is, in fact, intentional.