which is the first developed country
Developed countries, ie industrialized countries, are called countries that have high growth rates according to some standards. Who these standards are and which countries fall under the category of industrial or developed countries is a controversial subject
Economic standards are often included in this discussion. One such standard is per capita income. Countries whose per capita income is higher per capita GDP are counted in developed or industrialized countries. The second standard is industrialization. The countries whose economy is dependent on industry trades are called industrial countries.
Other parameters include the Human Development Index, which includes life expectancy and education along with national income. Countries that are competing to become developed countries are called developing countries. Developing countries are also called third world countries.
If we go by the economy, purchasing power, military size, and power then the United States Of America is the first developed straight from the time of World War 1 and still now.