Trade between the U.S. and Mexico has more than doubled since NAFTA went into effect. Most of this trade crosses the border by truck. This report addresses congressional concern that the border area was shouldering a disproportionate share of the costs of increased trade activity and that congestion problems related to expanded traffic were not being adequately addressed. It provides information and analysis on (1) the nature of commercial truck traffic congestion at the southwest border; (2) the factors that contribute to congestion; and (3) the actions, including programs and funding, that are being taken to address these problems. Charts and tables.