U.S. consumers expanded their borrowing at a slower rate in June compared to the prior month.

The Federal Reserve says that overall credit rose by $18.3 billion in June to $3.17 trillion total. That's down from a gain of $21.5 billion in May.

The smaller increase suggests that consumers remain sheepish about spending, which could limit how fast the economy can grow. Rising debt loads are generally a sign of greater confidence in the economy and fuel faster growth.

Auto and student loans drove much of the gains in June, up $16.2 billion. They have risen 8.4 percent year-over-year.

Credit card debt increased by a slight $2.1 billion in June. The increase in credit card debt over the past year has been 1.3 percent, evidence that consumers are restrained.