What American state in 2015 had the largest state budget in the U.S.?

In the U.S. in 2015, the State of California had the largest state budget. On June 25, 2015, Governor Brown signed the 2015–16 Budget Act, spending $167.6 billion from the General Fund and other state funds. General Fund appropriations were $115.4 billion in total, only $900 million more than the revised 2014–15 spending level. However, the small increase needed to be put in context. Surging state revenues boosted 2014–15 spending far above the levels approved by the Legislature in June 2014. The 2015–16 budget represented a $7.4 billion increase, or 6.9% expand, over the revised 2014–15 spending plan.

In California, spending increases date back to $56 billion in 1998. Currently, the large budget seeks to address existing and potential needs. California, with 12% of the U.S. population, now has one-third of the nation's welfare recipients. California has the third highest per capita spending on welfare among the states, as well as the highest spending on welfare in total dollar amounts. In prior years, California's total debt was greater than $265 billion. In June 2013, Governor Brown signed a balanced budget (no deficit) for the state, its first in decades; but, the state's debt remained at least $132 billion for a few years.

The economy of California is large enough to be comparable to that of any very large country. In 2013, the gross state product (GSP) was about $2.203 trillion, the largest in the U.S. See: https://en.wikipedia.org/wiki/California