Business activity in the Chicago area accelerated unexpectedly in February, adding to signs manufacturing gains will be sustained in 2014.

The Institute for Supply Management-Chicago Inc. said its business barometer increased to 59.8 this month from 59.6 in January. The median forecast of 53 economists in a Bloomberg survey called for the index to fall to 56.4. Readings greater than 50 signal growth.

Car sales, home construction and consumer spending continue to boost the outlook for manufacturers, which make up 12 percent of the economy. Faster wage growth and more job creation would lead to bigger and sustained gains.

Economists’ projections ranged from 53 to 60. The national factory index, produced by the Tempe, Arizona-based Institute for Supply Management probably rose to 52 in February from 51.3 the prior month, according to the median projection in a Bloomberg survey. That report is due March 3.