Increase in population.
Workers are going to developed countries in search of better-paying jobs.
natural increase + net migration = population change
b mass migration
Population density
The U.S. population increase is primarily driven by a combination of natural increase (more births than deaths) and international migration (people moving to the U.S. from other countries). Both factors contribute to the overall growth of the population.
Migration can affect population distribution by causing the population of one area to increase while simultaneously decreasing the population of another. This can also cause one area to be more densely populated than another.
One major demographic change observed in developed countries in the twenty-first century is the aging population, with individuals living longer and birth rates declining. This shift has implications for healthcare systems, pension programs, and workforce composition. Additionally, there has been an increase in cultural diversity and migration patterns, contributing to changes in societal makeup and dynamics.
The size of a population can get larger with no influences from migration if birthrate is greater than the death rate. This results in a natural increase in population size due to more individuals being born than those dying.
The increase in the proportion of the population residing in the towns brought about by migration of rural populations into towns and cities
That's a terrible answer and there is absolutely no logic backing it. First you need to understand the meaning of migration, which is the movement of people both ways - people leaving and coming into a country. Migration may cause a population increase, undoubtedly if there are more people coming into a country than going out, but this would also also increase a countries demand for services and facilities, opening up jobs in fields like construction, healthcare etc and reducing the unemployment rate which results in more tax revenue and national output which will increase the economy and leave the government with more money to spend as well as more personal income. An increase in population is not always a bad thing if it is done in a controlled way.
Migration can either increase or decrease the density of an area. If more people move into an area, the density will increase. Conversely, if people leave an area, the density will decrease. Migration patterns can also affect the composition and distribution of the population within an area.