import pandas as pd
 import re
 import urllib2
 data = urllib2.urlopen('http://www.census.gov/acs/www/Downloads/data_documentation/pums/DataDict/PUMSDataDict13.txt')

 ## replace newline characters so we can use dots and find everything until a double
 ## carriage return (replaced to ||) with a lookahead assertion.
 data=data.replace('n','|')

 datadict=pd.DataFrame(re.findall("([A-Z]{2,8})s{2,9}([0-9]{1})s{2,6}|s{2,4}([A-Za-z-() ]{3,85})",data,re.MULTILINE),columns=['variable','width','description'])
 datadict.head(5)

+----+----------+-------+------------------------------------------------+
|    | variable | width | description                                    |
+----+----------+-------+------------------------------------------------+
| 0  | RT       | 1     | Record Type                                    |
+----+----------+-------+------------------------------------------------+
| 1  | SERIALNO | 7     | Housing unit                                   |
+----+----------+-------+------------------------------------------------+
| 2  | DIVISION | 1     | Division code                                  |
+----+----------+-------+------------------------------------------------+
| 3  | PUMA     | 5     | Public use microdata area code (PUMA) based on |
+----+----------+-------+------------------------------------------------+
| 4  | REGION   | 1     | Region code                                    |
+----+----------+-------+------------------------------------------------+
| 5  | ST       | 2     | State Code                                     |
+----+----------+-------+------------------------------------------------+

datadict_exp=pd.DataFrame(
re.findall("([A-Z]{2,9})s{2,9}([0-9]{1})s{2,6}|s{4}([A-Za-z-();<> 0-9]{2,85})|s{11,15}([a-z0-9]{0,2})[ ].([A-Za-z/-() ]{2,120})",
           data,re.MULTILINE))
 datadict_exp.head(5)

+----+----------+-------+---------------------------------------------------+---------+--------------+
| id | variable | width | description                                       | value_1 | label_1      |
+----+----------+-------+---------------------------------------------------+---------+--------------+
| 0  | DIVISION | 1     | Division code                                     | 0       | Puerto Rico  |
+----+----------+-------+---------------------------------------------------+---------+--------------+
| 1  | REGION   | 1     | Region code                                       | 1       | Northeast    |
+----+----------+-------+---------------------------------------------------+---------+--------------+
| 2  | ST       | 2     | State Code                                        | 1       | Alabama/AL   |
+----+----------+-------+---------------------------------------------------+---------+--------------+
| 3  | NP       | 2     | Number of person records following this housin... | 0       | Vacant unit  |
+----+----------+-------+---------------------------------------------------+---------+--------------+
| 4  | TYPE     | 1     | Type of unit                                      | 1       | Housing unit |
+----+----------+-------+---------------------------------------------------+---------+--------------+