"There are many states in America."
Translation:Multae civitates sunt in America.
It is indeed a gender thing. multi is the maculine (nominative plural) form while multae is the feminine (nominative plural).
Adjectives do not need to agree in declension, so endings will be different. Both iuvenes and civitates are 3rd declension nouns while multi follows the second declension and multae follows the first declension.
Here, multae is used since it is the feminine form and matches with civitates in case, number, and gender.
If civitates was masculine, then multi would have been used.
The cases multae can be: (all feminine) nominative plural, vocative plural, genitive singular, and dative singular.
The cases multi can be: (mostly masculine, will note otherwise) nominative plural, vocative plural, genitive singular (also used for the neuter).
Names of cities, towns, small islands (only big enough to have one city or town on them) and a handful of other nouns (like domus) are able to use the locative case that was slowly disappearing.
For Roma, since it is a city, it has the locative case Romae. America is not a city, town, etc. so it is not able to use the locative and must use something else to express location (here in + ablative case).
Yes, civitates is feminine plural. The singular, as you probably know, is civitas.
The stem is cīvi-tāt- 'community; (city-)state', a derivative of cīvi-s 'citizen' (i.e., literally "citizen-ship" or rather "citizen-ry"). Nominative singular ending is /-s/, nominative plural /-ēs/. The nominative singular cīvitās is a reduced form of cīvitāss from /cīvitāt-s/ (by assimilation ts > ss). The plural is straight-forwardly /cīvitāt-ēs/.
There are still some nominative singular forms spelled with a double -ss in Old Latin (e.g., in Plautus), such as mīless for Classical mīles 'soldier' < mīlets < /mīlit-s/ , cf. Nom. Plur. /mīlit-ēs/.
There are also many countries in America / the Americas. America is the name of the North and South American continents, together. There is no country named America. The country that they are referring to is called the United States of America (USA). They are one of the countries in North America. Their country didn't exist in the time of the Romans. The land mass was there but it was owned by several separate native tribes. The Romans knew nothing about them.
If you ever run into Multi civitates sunt in America again, report it if it translates to the same as this sentence here. I have never seen the sentence in this course and suspect you misremembered.
Multi can not go with civitates since they do not match in grammatical gender. That is why multae is used.
Civitas definitely has a large variety of translations.
'Municipality' or 'community' would definitely be decent translations in Classical Latin in my opinion. Civitas tends to refer to a city, town, etc. and its surrounding area that is under its control, hence their use of 'state'. I am not sure if say the states in the USA (I am sure other countries in the Americas also have states, but I don't know which) would be called civitates by the Romans due to how big they are, but based on Lewis and Short, sometimes several cities would be considered apart of a civitas. If anyone else knows more I hope they can add to this.
It seems that a some point it was used as if it was equivalent to the urbs but that seems to be later Latin.