The structure of etheniums ground state was in dispute for many years, but it was eventually agreed to be a non-classical structure, with the two carbon atoms and one of the hydrogen atoms forming a three-center two-electron bond.  Calculations have shown that higher homologues, like the propyl and n-'butyl cations also have bridged structures.  Generally speaking, bridging appears to be a common means by which 1° alkyl carbocations achieve additional stabilization.  Consequently, true 1° carbocations (with a classical structure) may be rare or nonexistent.