Darlington stretched their unbeaten league run to six games but looked
unconvincing against a Southend side without an away win since March.
The visitors dominated the match but failed to take their chances.
Midfielder Mark Gower was dominant midfield middle for the Shrimpers, and he went closest to breaking the deadlock in the first half.
Twice he fired narrowly wide, while United striker Drewe Broughton headed straight at Darlington keeper Michael Price.
Darlington rarely threatened and Southend substitute Tes Bramble shot wide in the 84th minute then missed a glorious opportunity when he fired wide in the dying seconds.
Darlington: Price, Hutchinson, Valentine, Liddle, McGurk,
Nicholls, Clark, Keltie, Hughes, Clarke, Conlon. Subs: Bossy,
Mellanby, Convery, Robson, Coghlan.
Southend: Flahavan, Jupp, Stuart, Cort, Warren, Fullarton,
Gower, Maher, Odunsi, Broughton, Constantine. Subs: Jenkins,
Bramble, Smith, McSweeney, Robinson.
Referee: M Pike (Cumbria).