The PATRICIA and RACETRACK particle tracking programs have been compared by tracking on a simple lattice. The dynamic aperture was found to decrease as the number of passes through the lattice per run increased from 20 to approx. 300, and it remained constant for longer runs. The dynamic apertures found by the two programs are consistent. The dependence of the dynamic aperture on horizontal tune near a decapole resonance was investigated. RACETRACK and PATRICIA showed decreases in the aperture on opposite sides of the resonance. A second set of studies was made with PATRICIA in which the dynamic apertures of lattices consisting of cells of the types used for the Reference Designs Study were determined when random multipole errors of the dipoles were included. The dependence of aperture on the number of cells in the lattice was determined. Finally, a comparison of magnet types suggested for the SSC was made by determining the aperture of lattices containing these magnets.