You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
New_York_City

Context:
In 1898, the modern City of New York was formed with the consolidation of Brooklyn (until then a separate city), the County of New York (which then included parts of the Bronx), the County of Richmond, and the western portion of the County of Queens. The opening of the subway in 1904, first built as separate private systems, helped bind the new city together. Throughout the first half of the 20th century, the city became a world center for industry, commerce, and communication.

Question:
In what year did the subway begin operation?

1904