By law, the city's skyline is low and sprawling. The federal Height of Buildings Act of 1910 limits building height based on the width of the adjacent street, with maxima of on residential streets and on commercial ones. Despite popular belief, no law has ever limited buildings to the height of the United States Capitol or the Washington Monument, which remains the district's tallest structure. City leaders have cited the height restriction as a primary reason that the district has limited affordable housing and its metro area has suburban sprawl and traffic problems.