Here are 3 different sources:
Transport and Communications Bulletin for Asia and the Pacific, No. 82 “Combatting Congestion” by, Yves Boquet, 2013
Excerpt:
ABSTRACT
The urban density of Manila, the capital of the Philippines, is one the highest of the world and the rate of motorization far exceeds the street capacity to handle traffic. The setting of the city between Manila Bay to the West and Laguna de Bay to the South limits the opportunities to spread traffic from the south on many axes of circulation. Built in the 1940’s, the circumferential highway EDSA, named after historian Epifanio de los Santos, seems permanently clogged by traffic, even if the newer C-5 beltway tries to provide some relief
Why was EDSA called Highway 54 ?
Construction of what was then called the North–South Circumferential Road began in the 1930s under President Manuel L. Quezon. The construction team was led by engineers Florencio Moreno and Osmundo Monsod.
The road, starting from the North Diversion Road (today the North Luzon Expressway) and ending at the current Magallanes Interchange with the South Luzon Expressway, was finished in 1940 shortly before the outbreak of World War II and the subsequent Japanese Occupation. After the independence of the Philippines from the United States in 1946, the road was renamed Avenida 19 de Junio (June 19 Avenue), after the birth date of national hero Jose Rizal.
History of Edsa, Wikipedia
Construction of what was then called the North and South Circumferential Road began in 1939 under President Manuel L. Quezon.[12] The construction team was led by engineers Florencio Moreno and Osmundo Monsod.[1]
The road, starting from North Bay Boulevard in Navotas and ending at Taft Avenue (formerly known as Taft Avenue Extension / Manila South Road) in Pasay, then in the province of Rizal,[13] was finished in 1940 shortly before the outbreak of World War II and the subsequent Japanese Occupation. It was then known as the Manila Circumferential Road or simply as Circumferential Road.[14][15] It was also renamed to Highway 54 and thus designated as Route 54.[16][17] Due to the route number, there was a common misconception on that time that the avenue is 54 kilometers (34 mi) long.[1] The present-day North EDSA section in Caloocan and Quezon City was referred to as Calle Samson (Samson Street), while its section in Pasay was also known as P. Lovina Street. After the independence of the Philippines from the United States in 1946, the road was renamed Avenida 19 de Junio (June 19 Avenue), after the birth date of national hero José Rizal.[1]