City authorites are bulldozing vacant lots in Chicago, Pittsburgh and Detroit. Hundreds of vacant lots can be a problem for cities. Clearing these vacant lots is the first step to building new housing that is badly needed today. Detroit's population has fallen by two thirds, Pittsburgh by half, and Chicago by a quarter since 1950's. Detroit's land bank holds 63,000 vacant lots, Pittsburgh has 13,000 city owned lots being transferred to a land bank. Chicago has 10,000 vacant lots and 16,000 lots caught in a mess of unpaid taxes and unpaid fees. The city is working on new laws to speed up the clearing and development of these lots. Many are in Black and Latino neighborhoods once known to be redlined, meaning the banks denied the places mortgages and speculators engaged in blockbusting to sell declining white neighborhoods from the shift to suburbs to black people.