A report from the Minnesota Department of Transportation out Tuesday found that congestion on metro area highways and freeways jumped by 2 percentage points in 2015, and predicted that roads are likely to get more crowded and slower.

According to the Metropolitan Freeway System Congestion Report, the freeways in the Twin Cities were congested 23.4 percent of the time, up from 21.4 percent in 2014. The report attributed the jump to a number of factors, including lower gas prices, a robust economy, population growth and that people are driving more.

And motorists are creeping along more, too. Using field observations and data collected from 3,500 sensors embedded in the pavement, MnDOT measured congestion levels on 758 miles of Twin Cities freeways and found that traffic flowed at speeds less than or equal to 45 miles per hour nearly a quarter of the time during the morning and afternoon rush hours. The readings were taken in October 2015, a month when traffic conditions are most typical.