May Day immigration protests in U.S. smaller than past 2 years

(CNN) - Thousands of demonstrators - but not as many as in past years - gathered in U.S. cities Thursday to protest federal immigration raids and deportations and to call for comprehensive immigration reform, including opportunities for the country's illegal immigrants to gain citizenship.

In Chicago, Illinois, about 3,000 to 4,500 people marched around the city's downtown area, police said. Several people carried a large American flag; others held banners or signs, video showed.

The early estimate of participants paled greatly from protests in Chicago in past years - in 2007, numbers reached about 150,000, and the year before, estimates ranged from 400,000 to 700,000.