Soil compaction lowers agricultural productivity and profitability in the Mid-Atlantic region by restricting growth and water uptake by plant roots. A field experiment was conducted on Maryland’s coastal plain. Three soil compaction levels were applied at the start of the experiment (none, medium, high) followed by shallow disking and planting 4 winter cover crops (rye (Secale cereale L.), forage radish (FR, Raphanus sativus L), rapeseed (Brassica napus) and no cover). Rye has a fibrous root system, whereas FR and rapeseed are tap-rooted plants of the Brassicaceae family. Our objectives were (1) to evaluate effects of soil compaction on root penetration, (2) to determine effects of cover crops on the macro-porosity of compacted soil layers; (3) to quantify root penetration of corn on compacted soils as influenced by winter cover crops. Cover crop root penetration was determined by the core break method. Macroporosity was estimated by air permeometer. Corn root penetration was estimated by core break and by monitoring soil water in the Ap and B horizons. Compaction significantly reduced shoot and root biomass of all 3 cover crops. FR had more aboveground biomass, higher N tissue concentrations, and took up nearly twice as much N as rye in both compacted and non-compacted soils. Compaction stimulated a much larger proportion of roots in the upper, loosened 8 cm. Below this depth, rooting was severely reduced for rye, moderately for rapeseed and not at all for FR. FR had 2 to 4 times as many roots in the compacted layer than rye and rapeseed. Air permeability was also higher in soil following FR and rapeseed. In summer, subsoil water following FR was the lowest, suggesting enhanced subsoil water use by corn. We conclude that these two Brasssica cover crops may help ameliorate effects of compaction on agricultural land.