Neither side could find the back of the net in sodden conditions at Robert F Kennedy Memorial Stadium on Friday.
The result, however, was still good enough for East pacesetters United to claim a post-season berth with three games remaining.
United are top of the East with 52 points from 31 matches, six clear of second-placed Sporting KC.
Ben Olsen's United came into the game knowing a draw would be enough, while Sporting KC were desperately short of form having lost five of their past six league fixtures.
United were happy to play on the counter-attack during the early exchanges and it almost resulted in a goal after 10 minutes as Chris Pontius' deflected shot tested Sporting KC goalkeeper Andy Gruenebaum.
The home side had another sight on goal three minutes later, though Fabian Espindola's effort flashed wide of the far post.
Antonio Dovale came close for United in the 28th minute, forcing Gruenebaum into a save.
The second half started in similar fashion, with United engineering another swift move that went wide of the post in the 58th minute.
Sporting KC had a golden opportunity to break the deadlock with 14 minutes remaining but CJ Sapong was denied by United keeper Bill Hamid as the capital club returned to the play-offs having collected just 16 points last term.
