Kenny McLean’s well-taken opener (39) was answered before half-time by Stuart Armstrong (43), a point each leaving the visitors two short of Inverness and St Mirren just four clear of bottom side Ross County having played two games more.
In the context of their dismal home record – 10 defeats in 11 league games before kick-off – a draw represented a decent return for Gary Teale’s side, but they had enough chances before and after the break to win an open game.
McLean misssed the first of them, failing to beat Radoslaw Cierzniak after a poor Keith Watson back-pass put him through on goal, and Yoann Arquin had a shot cleared off the line later in the first half.
The breakthrough came in classy fashion, McLean lifting the ball over Sean Dillon and prodding in a left-footed half-volley for his sixth goal of the season.
United had gone close themselves through Chris Erskine, and the lead was shortlived as Gary Mackay-Steven’s burst allowed Nadir Ciftci to square for Armstrong, who took a touch and volleyed inside the near post.
Celtic-bound Mackay-Steven remained a threat after the break, but St Mirren came closest to winner as McLean again got clear only to fluff his finish.