WASHINGTON — Calling texting and cellphone use “a national epidemic,” Transportation Secretary Ray LaHood laid out a blueprint today for stepped-up federal efforts and pressure on states to crack down on distracted driving.

Studies show the problem is particularly acute among teenage and young adult drivers, LaHood said.

“We need to teach kids, who are the most vulnerable drivers, that texting and driving don’t mix,” LaHood said at a news conference. He pointed to a recent case in which a texting teen driver involved in a fatal accident was ordered jailed for a year.

The Transportation Department is also awarding $2.4 million to Delaware and California for pilot projects to combine more police enforcement with publicity campaigns against distracted driving. Similar pilot projects in Syracuse, N.Y., and Hartford, Conn., were shown to successfully reduce distracted driving, LaHood said.

LaHood called on automakers to support voluntary government guidelines to ensure dashboard technologies increasingly being added to cars won’t distract drivers. But he rejected making the guidelines mandatory.

LaHood has made his opposition to distracted driving a signature issue for the Obama administration. When he was appointed transportation secretary three years ago, 18 states had anti-texting laws and seven had bans on both texting and hand-held cellphone use. Today, 39 states ban texting, and 10 ban both texting and hand-held cellphone use.

States with no restrictions on drivers’ cellphone use or texting are Arizona, Florida, Hawaii, Mississippi, Missouri, Montana, New Mexico, Oklahoma, South Carolina, South Dakota and Texas, according to the Governors Highway Safety Association. Although Hawaii doesn’t have a state law, all of the state’s counties have enacted distracted-driving ordinances, the association said.

LaHood declined to endorse bans on hands-free phones, saying the department wants to conduct a study of real-world cellphone use by drivers first.

The National Transportation Safety Board has called for a complete ban on cellphone use by drivers, including the use of hands-free phones. Most studies show that hands-free conversations are just as distracting to drivers as those involving hand-held phones. Scientists says it’s hard for drivers to divide their attention been conversation and the road.