In general, articles are not used with proper noun. Articles are mostly used with common noun but we always have exceptions to the rule. Definite article (the) is commonly use for proper now.
Article can be use before a proper now that refers to a country that has plural names. - The Netherlands, The Caribbean Islands.
Article are use before a prepositional phrase - The United States of America.
They are also use with names of countries with kingdom and republic in them - She lives in the Republic of Congo.
Articles are use with names of geographical locations. - I am going to the Nile river.
They are use when you are referring to a family. - I visited the Johnsons yesterday. The Starks are generous.
Generally speaking, you should not use an article with a proper noun unless the proper noun has a prepositional phrase. A prepositional phrase are words like: of, in, on, and under. Proper nouns such as Berkley or Louisiana will not need an article because there is no prepositional phrase.
Proper nouns like the United States of America will need an article because there is a prepositional phrase in the name. Use a definite article when referring to geographical terms: the Nile, the Empire State Building. Also use a definite article when referring to the plural—the Great Lakes, the Galapagos Islands.