The short answer is a lack of funding for the Social Security Administration from Congress. Office of Hearings Operations (OHO) have not had an increase in funding in many years. SSA officials have told Congress that they need more Social Security Administrative Law Judges and support staff to administer the hearings. However, Congress has yet to provide that money. This issue has been in the news lately.
In Minnesota KARE 11 did an investigation on this very issue (http://www.kare11.com/mobile/article/news/investigates-thousands-die-waiting-for-disability-benefits/89-501864123). This report noted that approximately 10,000 people died waiting for hearings last year. The average wait time is 590 days. In Minneapolis, the wait time is longer 22 months.
In the New York area the wait time is around 700 days according to the New York Daily News (http://www.nydailynews.com/new-york/feds-bureaucratic-hellscape-gnaws-new-yorkers-health-hope-article-1.3719577).
In Florida the wait time is around 619 days with the Miami area having a wait time of around 725 days (http://www.tampabay.com/opinion/editorials/Editorial-Shorten-waits-for-disability-benefits_163494113).
This backlog has very real and has detrimental consequences for Social Security Claimants. The Atlanta Journal Constitution detailed the story of a woman who was caught up in the backlog (http://www.myajc.com/news/national-govt–politics/this-atlanta-woman-lost-her-home-waiting-for-disability/Nd0uGeSLLQD1bSYz6bHBKM/). While waiting for her hearing she lost her car, her children’s college funds, her savings and her home. Eventually a judge awarded her case but it was not before her house had been foreclosed on. Claimants can contact their federal representatives, their Representatives and Senators, to encourage them to allocate more money for the Social Security budget. Additionally, if you are experiencing what is called “dire financial need” which is usually defined as a lack of food, health care or shelter, sometimes a hearing can be expedited. However, even an expedited hearing doesn’t happen immediately.