The first underground line of the subway opened on October NUMBER@1 , NUMBER@2 , almost NUMBER@3 years after the opening of the first elevated line in LOCATION@1 , which became the IRT Ninth Avenue Line .

The IRT main line , which is considered to be the first LOCATION@1 `` subway '' line , opened in NUMBER@2 ; however , the Ninth Avenue Line , a predecessor elevated railroad line , operated its first trial run on July NUMBER@4 , NUMBER@5 .
