The low-income housing tax credit (LIHTC) is the most successful aff ordable housing production and preservation program in the nation.

Since its creation 25 years ago, the LIHTC has helped to finance more than 2.4 million units for low-income Americans, according to the National Council of State Housing Agencies (NCSHA). And it generates about 120,000 more aff ordable homes each year.

Here is a look at the number of units financed through the LIHTC and housing bond programs from 1987 to 2009: 2,427,584 units nationwide, including Puerto Rico and Washington, D.C., by state, as provided by the NCSHA.

Each state receives a per capita allocation of tax credits each year. For calendar year 2011, the state LIHTC ceiling is the greater of $2.15 multiplied by the state population or $2,465,000, an increase from $2.10 and $2,430,000, respectively, in 2010. Nationwide, demand for the LIHTC is twice its supply with the majority of states using all or nearly all of their authority annually.