Present-day Lamar County was part of Red River County during the Republic of Texas. By 1840, population growth necessitated the organization of a new county. George Washington Wright, who had served in the Third Congress of the Republic of Texas as a representative from Red River County, was a major proponent of the new county. The Fifth Congress established the new county on December 17, 1840, and named it after Mirabeau B. Lamar, who was the first Vice President and the second President of the Republic of Texas.

In 1877, 1896, and 1916, major fires in the city forced considerable rebuilding. The 1916 fire destroyed almost half the town and caused an estimated $11 million in property damage. The fire ruined most of the central business district and swept through a residential area. The burned structures included the Federal Building and Post Office, the Lamar County Courthouse and Jail, City Hall, most commercial buildings, and several churches.

The city is home to several late-19th to mid-20th century stately homes. Among these is the Rufus Fenner Scott Mansion, designed by German architect J.L. Wees and constructed in 1910. The structure is solid concrete and steel with four floors. Rufus Scott was a prominent businessman known for shipping, imports, and banking. He was well known by local farmers, who bought aging transport mules from him. The Scott Mansion narrowly survived the fire of 1916. After the fire, Scott brought the architect Wees back to Paris to redesign the historic downtown area.

Paris was named the “Best Small Town in Texas” by Kevin Heubusch in his book The New Rating Guide to Life in America’s Small Cities.