Pasig Day or Araw ng Pasig is celebrated yearly on July 2, the anniversary of the original town's foundation by the Augustinians. The former municipality of Pasig finally became Pasig City on July 1994 with the enactment of R.A. 7829. This year the city named for the river that flows through it is 432 years old.
According to the late Dr. Jose Villa Panganiban, the word Pasig is an old Sanskrit word referring to a “river flowing from one body of water to another” – in the case of Pasig River, from Laguna de Bay to Manila Bay. On the other hand, there is also a legend that the name came about from a man named Virgilio being carried away by the current after the boat he was riding on with his lover Paz capsized. He kept yelling for Paz to help him, "Paz sigue me!" He was carried for such a distance that after a while he could only be heard shouting "Paz sig!", hence the name. True or not, it makes for a rather fascinating tale.
Pasig was formerly the capital of the province of Rizal until 1975. In fact Rizal, which used to wrap around Manila, formerly included Quezon City and Pasay City, now both highly developed cities themselves.
At present Pasig City is one of the Philippines' top industrial, commercial and business districts, as evidenced by all the tall buildings which make up its modern skyline.
Its a shame Pasig Day this year falls on a Saturday, as it is considered a special non-working holiday within the city. I work in Pasig. :-)