Many countries would have some cities, municipalities or localities that we can call their "mixing bowl", which means people residing in them come from different parts or regions of the country. Baguio City, Philippines is among the cities that have now so many residents that come from different regions and provinces of the country. For one thing, it is the cool climate that they really come to like. There is no other city in the Philippines that would have an almost year-round cool climate.
Many migrants then, came from the nearby province of Pangasinan. The reason they have a good number of residents in Baguio was due to gold and copper mines that flourished around Baguio city in the 1900s. The promise of good pay in the mining industry was so attractive then. That was also some reason for those from other provinces to migrate to Baguio. Until now, even people assigned by companies to their city's branch office hardly want to leave the city if they are to be re-assigned to another place after a few years.
A good number of old-timer residents also come from the province of Batangas. The Batanguenos are good in doing business and they could have been the 'Levis Strauss' for the several mines surrounding the city. Migrants at that time learned to speak the more common 'Ilocano' dialect then. The national Pilipino language was not spoken by much by locals. In fact, most of the locals and natives even spoke English better than Tagalog until the late 60s!
Tagalog or the Pilipino language became more spoken when migrants from Central Luzon, Southern Luzon, Visayas and Mindanao increased. They easily understood more the national language and spoke it even in a heavy accent. It can also be noticed that people from the southernmost tip of the Philippines, those who are with the Islam faith, have also increased in number! They are mostly ambulant vendors and are quite making good. To identify them in Baguio City, they wear robes and caps that Muslims don. The women mostly still wear their 'bandanas' but do not cover their face.
It is a lot easier now to communicate to almost all residents in Baguio City in Tagalog and English too.