A reverse migration program, launched 21 years ago by then Istanbul Mayor Recep Tayyip Erdoğan, has seen more than 157,000 people return to their hometowns from the country's most populated city, according to a report in the Habertürk daily.

The municipality's initiative covers transportation fees for families or free bus tickets.

Istanbul, a magnet for migration from other parts of Turkey and abroad, is burdened with 14.6 million people. It has a population density of over 2,700 people per square kilometer. In recent years, a construction boom, helped by a growing economy, has strived to meet rising demand for housing in the city straddling Asia and Europe.

The program, initially oversaw by municipal police, is now being carried out in coordination with social services and mainly targets impoverished families. Families need to document their financial status to be granted migration incentives. The Istanbul Metropolitan Municipality will launch a new contract next month for companies to handle the transportation.

In the past three years, some 13,083 families have left Istanbul for their hometowns on the program. Along with the families who sought to set up a new life in the city but failed to prosper, the program covers students and patients who undergo treatment in Istanbul but cannot afford to travel back to their hometowns.

Although Turkey is more occupied with the issue of the growing population of migrants from other countries, like the millions of Syrian refugees fleeing the civil war in their country, internal migration remains a concerning issue.

The provinces that have suffered the most from internal migration are Van, Erzurum, and Malatya, according to Turkish Statistical Institute (TurkStat) figures.