An analysis of barangay population densities in the light of existing conditions in each respective area shows a pattern by which population is concentrated (Refer to Table 2.08 and Map 7). In Barangay Addition Hills, for example, the gross population density measures extra high despite being the second largest barangay in the city and the presence of large institutional areas and open spaces. Being a Planned Unit Development Area (PUD), it promises housing opportunities with government subsidies and the necessary amenities for a respectable living condition, and further, accessibility to employment and livelihood opportunities. The existence of informal settlements and sites intended for socialized housing projects appear to be common in other barangays with high to extra high densities.

Another major contributing factor is the presence of the railroad traversing most of these barangays that have consistently high densities. In the early days when the rail system is the popular mode of travel, distance-wise and travel time considered, migrants tend to arrive by train, seeking accommodations as much as possible in the vicinity of railway stations. In Mandaluyong City, until the 1970’s when the railway system is still operational, four (4) stations are located in Barangays Daang Bakal, San Jose, Hulo and Barangka Ilaya, giving credence to the above observation. But in this case, it can be assumed that the migrants established permanent residences in these barangays, later expanding to adjoining barangays.

Furthermore, the historic Pasig River in its glorious days of steamers and ferry boats provided another means of entry to migrants as manifested by a number of ‘Tawiran’ stations along the river banks. In addition, various industries lining the coast of Mandaluyong City served as a strong magnet to people seeking better economic opportunities. These could be associated with concentrated residences in barangays along Pasig River.

A graphical representation of the total population by barangay (Figure 2.03) shows the obvious difference in the distribution of population in the city. Taking into account the proportions of area and population of each barangay in relation to the total area and population of Mandaluyong City (Table 2.04), the Index of Concentration is computed as 0.1074. This means that about 10.75% of the total population will have to be redistributed in order to attain a completely uniform distribution of population in the city.